58 results on '"J Argibay"'
Search Results
2. Caffeine-induced immobilization of gating charges in isolated guinea-pig ventricular heart cells
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Jérôme Leroy, François Gannier, Claire O. Malécot, Jacques M. Lignon, and J Argibay
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Pharmacology ,Membrane potential ,medicine.medical_specialty ,Sarcolemma ,Voltage-dependent calcium channel ,Chemistry ,Gating ,Electrophysiology ,Endocrinology ,Internal medicine ,medicine ,Biophysics ,Myocyte ,Repolarization ,Patch clamp - Abstract
The effects of 10 mM caffeine (CAF) on intramembrane charge movements (ICM) were studied in isolated guinea-pig ventricular heart cells with the whole-cell patch-clamp technique. In the presence of CAF, the properties (voltage dependence, maximum QON[Qmax], availability with voltage) of QON charge activated from −110 mV were barely affected. Following a 100 ms prepulse to −50 mV to decrease the participation of charges originating from Na channels, the voltage dependence of QON was shifted by 5 mV (negative component) and by 10 mV (positive component) towards negative potentials, and Qmax was depressed by 16.5%. CAF drastically reduced in a time- and voltage-dependent manner QOFF on repolarization to −50 mV, the effects being greater at positive potentials. CAF-induced QOFF immobilization could be almost entirely removed by repolarization to voltages as negative as −170 mV. In these conditions, the voltage-dependence of QOFF (repolarization to +30 to −170 mV) was shifted by 17 mV (negative component) and 30 mV (positive component) towards negative potentials, suggesting an interconversion into charge 2. Most of CAF effects were suppressed when the sarcoplasmic reticulum (SR) was not functional or when the cells were loaded with BAPTA-AM. We conclude that CAF effects on ICM are likely due to Ca2+ ions released from the SR, and which accumulate in the subsarcolemmal fuzzy spaces in the vicinity of the Ca channels. Because CAF effects were more pronounced on QOFF than on QON the channels have likely to open before Ca2+ ions could affect their gating properties. It is speculated that such an effect on gating charges might contribute to the Ca-induced inactivation of the Ca current. British Journal of Pharmacology (2002) 135, 721–734; doi:10.1038/sj.bjp.0704520
- Published
- 2002
3. cGMP-mediated inhibition of cardiac L-type Ca2+current by a monoclonal antibody against the M2ACh receptor
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Laurent Sallé, N. Peineau, J Argibay, Johan Hoebeke, and José Nascimento
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medicine.medical_specialty ,Patch-Clamp Techniques ,Calcium Channels, L-Type ,Phosphodiesterase Inhibitors ,Physiology ,medicine.drug_class ,Heart Ventricles ,Guinea Pigs ,Muscle Fibers, Skeletal ,8-Bromo Cyclic Adenosine Monophosphate ,In Vitro Techniques ,Monoclonal antibody ,Membrane Potentials ,Guinea pig ,1-Methyl-3-isobutylxanthine ,Quinoxalines ,Internal medicine ,Muscarinic acetylcholine receptor ,medicine ,Extracellular ,Animals ,L-type calcium channel ,Enzyme Inhibitors ,Receptor ,Cyclic GMP ,Autoantibodies ,Oxadiazoles ,Receptor, Muscarinic M2 ,Guanosine ,Chemistry ,Myocardium ,Colforsin ,Isoproterenol ,Autoantibody ,Antibodies, Monoclonal ,Cell Biology ,Adrenergic beta-Agonists ,Receptors, Muscarinic ,Molecular biology ,Endocrinology ,cGMP-dependent protein kinase - Abstract
The effects of a monoclonal antibody (B8E5) directed against the second extracellular loop of the muscarinic M2receptor were studied on the L-type Ca2+currents ( ICa,L) of guinea pig ventricular myocytes using the whole cell patch-clamp technique. Similar to carbachol, B8E5 reduced the isoproterenol (ISO)-stimulated ICa,Lbut did not significantly affect basal ICa,L. Atropine blocked the inhibitory effect of B8E5. The electrophysiological parameters of ISO-stimulated ICa,Lwere not modified in presence of B8E5. Inhibition of ICa,Lby B8E5 was still observed when intracellular cAMP was either enhanced by forskolin or maintained constant by using a hydrolysis-resistant cAMP analog (8-bromoadenosine 3′,5′-cyclic monophosphate) or by applying the phosphodiesterase inhibitor IBMX. The effect of B8E5 was mimicked by 8-bromoguanosine 3′,5′-cyclic monophosphate, a potent stimulator of cGMP-dependent protein kinase, and prevented by a selective inhibitor of nitric oxide-sensitive guanylyl cyclase {1 H-(1,2,4)oxadiazolo[4,3-a]quinoxaline-1-one}. These results indicate that the antibody B8E5 inhibits the β-adrenergic-stimulated ICa,Lthrough activation of the M2muscarinic receptor and further suggest that the antibody acts not via the classical pathway of decreasing intracellular cAMP, but rather by increasing cGMP.
- Published
- 2001
4. Block of gating currents related to K+ channels as a mechanism of action of clofilium and d-sotalol in isolated guinea-pig ventricular heart cells
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J Argibay and Claire O. Malécot
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Pharmacology ,medicine.medical_specialty ,Voltage-dependent calcium channel ,Chemistry ,Sodium channel ,Potassium channel blocker ,Clofilium ,Gating ,Potassium channel ,Endocrinology ,Internal medicine ,medicine ,Biophysics ,Repolarization ,Patch clamp ,medicine.drug - Abstract
The possibility that the class III antiarrhythmic drugs clofilium and d-sotalol might affect delayed rectifier potassium channels at the level of their gating currents was assessed with the whole-cell patch-clamp technique in guinea-pig isolated ventricular heart cells. Clofilium (up to 20 μM) and d-sotalol (1 μM) did not decrease the Na current, the L-type Ca current or the background K current iKl, but significantly depressed the time-dependent delayed outward K current iK. Clofilium partially decreased in a dose-dependent manner (1–20 μM) QON of intramembrane charge movements (ICM) elicited by a depolarizing pulse applied from a holding potential of −110 mV or following a 100 ms inactivating prepulse to −50 mV. D-sotalol (1 μM) also decreased QON. Channel density estimated from the clofilium-sensitive ICM closely matched that of the delayed rectifier channels. Clofilium and d-sotalol decreased QOFF seen on repolarization in a dose- and voltage-dependent manner. The kinetics of the decay of the OFF gating currents were not affected, and only the fast phase was depressed. In control conditions, QON availability with voltage was most of the time well described by two inactivating components. In the presence of clofilium and d-sotalol, a complex behaviour of QON availability was observed, unmasking additional components. The reactivation kinetics of QON after a 500 ms inactivating pulse to 0 mV was not affected. We conclude that delayed rectifier K channels significantly contribute to QON and QOFF of ICM in guinea-pig ventricular heart cells, besides Na and Ca channels, and that clofilium and d-sotalol directly interact with these K channels proteins by affecting their gating properties. Keywords: Intramembrane charge movements, K+ channels, native cardiac cells, class III antiarrhythmic drugs, clofilium, d-sotalol Introduction Intramembrane charge movements (ICM) in excitable cells result from molecular rearrangements of ion channel proteins under the impetus changes in the membrane potential. In mammalian cardiac cells, only sodium and calcium channels have been thought to give rise to ICM recorded with short depolarizing pulses, because of the much slower activation kinetics of the delayed rectifier potassium current (see Field et al., 1988; Bean & Rios, 1989; Hadley & Lederer, 1989, 1991a; Hanck et al., 1990; Shirokov et al., 1992; 1993). However, we have found more than two components of ICM in guinea-pig ventricular myocytes (Malecot & Argibay, 1996) which could not be entirely suppressed by the Na and Ca channels blockers lidocaine, tetracaine, nifedipine and D600 (Malecot et al., 1997a,1997b), although the underlying currents are blocked. However, compounds such as D600 or nitrendipine have been shown to be able to suppress all of the gating currents in heart cells, but at high concentrations that also affect potassium currents (e.g., Hadley & Lederer, 1991a). These results suggest that other channels might also contribute to ICM in heart cells. Moreover, recent studies of different expressed cloned potassium channels have revealed their fast gating currents (Larsson et al., 1996; Fedida, 1997), which are very similar in shape to those recorded in isolated heart cells. Therefore, we have re-investigated the pharmacological properties of ICM in freshly isolated guinea-pig heart cells and, in particular, we have tested the hypothesis of the presence of a component of ICM originating from the voltage-activated delayed rectifier K channels. Because several antiarrhythmic drugs have been shown to affect gating currents in many preparations, we have tested in this paper the possibility that the class III antiarrythmic drugs, clofilium and d-sotalol, blockers of iKs and of iKr (for review see Baro & Escande, 1993; Snyders, 1995), might affect delayed rectifier potassium channels at the level of their gating currents. We show here that ICM activating at positive potentials are sensitive to clofilium and d-sotalol at concentrations not inhibiting the Na or the L-type Ca channels but depressing the delayed outward K current in our recording conditions. To our knowledge, this is the first time that K channels are shown to significantly contribute to ICM in freshly isolated heart cells, besides Na and Ca channels. This new finding opens the door to a better understanding of the relationships between ICM and membrane excitability and to the future development of more powerful pharmacological compounds. A preliminary note on these experiments has been published (Malecot & Argibay, 1998).
- Published
- 1999
5. Ruthenium red as an effective blocker of calcium and sodium currents in guinea-pig isolated ventricular heart cells
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Virginie Bito, J Argibay, and Claire O. Malécot
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Pharmacology ,Membrane potential ,Ruthenium red ,Sarcoplasm ,chemistry.chemical_element ,Calcium ,chemistry.chemical_compound ,Sodium channel blocker ,chemistry ,Biochemistry ,Biophysics ,Myocyte ,Patch clamp ,Ion transporter - Abstract
1. The effect of ruthenium red on calcium and sodium currents was studied in guinea-pig isolated ventricular heart cells with the whole cell patch-clamp technique. 2. Ruthenium red very efficiently blocked the L-type calcium current in a dose-dependent manner. A significant block was observed for concentrations as low as 0.3 microM. Analysis of the dose-response curve with the logistic equation indicated an EC50 of 0.8 microM, a maximum inhibition of 85% reached at 5 microM, and a coefficient of 2.37. 3. There was no shift in the voltage-dependence of the Ca current activation, nor in that of its steady-state inactivation determined with a 1 s prepulse. However, removal of Ca current inactivation at positive voltage was considerably reduced in the presence of concentrations of ruthenium red above 1 microM. A slowing of the time-course of inactivation of the Ca current was also observed. 4. At 10 microM, a concentration generally used to block the sarcoplasmic Ca release channels or the mitochondrial Ca uptake, ruthenium red blocked 26.7+/-4.3% (n=8) of the sodium current, and slowed its inactivation time-course. No effect was observed on the voltage-dependence of the current activation or inactivation. The peak sodium current was also decreased at a 10 times lower concentration by 7.6+/-2.7% (n=3). 5. Thus, at concentrations used to assess intracellular Ca movements, ruthenium red induced in heart cells a significant block of both Ca and Na channels.
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- 1998
6. An agonist-like monoclonal antibody against the human β2-adrenoceptor
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J Hoebeke, Alfredo Mijares, Diane Lebesgue, Gerd Wallukat, J Argibay, and Claude Granier
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Patch-Clamp Techniques ,medicine.drug_class ,Trypanosoma cruzi ,Molecular Sequence Data ,Peptide ,Monoclonal antibody ,Epitope ,Membrane Potentials ,Immunoenzyme Techniques ,Epitopes ,Mice ,Radioligand Assay ,Heart Rate ,Tumor Cells, Cultured ,medicine ,Extracellular ,Animals ,Humans ,Amino Acid Sequence ,Receptor ,Adrenergic beta-2 Receptor Agonists ,Peptide sequence ,Pharmacology ,chemistry.chemical_classification ,biology ,Myocardium ,Antibodies, Monoclonal ,Adrenergic beta-Agonists ,Molecular biology ,Epitope mapping ,Biochemistry ,chemistry ,Fluorescent Antibody Technique, Direct ,biology.protein ,Antibody - Abstract
Monoclonal antibodies were produced against a peptide corresponding to the second extracellular loop of the human beta2-adrenoceptor. One of these monoclonals, inducing an agonist-like effect in neonatal rat cardiomyocytes, was used to define the structural and physiological basis of this activity. The epitope recognized by the antibody corresponds to the sequence Trp-Tyr-Arg-Ala-Thr-His-Gln-Glu as determined by peptide scanning. Analysis by alanine modification of the peptide epitope showed the importance of the Trp, and Glu residues in antibody recognition The apparent affinity of the antibody assessed either by surface plasmon resonance or by functional titration on its agonist-like activity showed a similar value (10(8) M(-1)). The antibody recognized the receptor in its native form as shown by immunofluorescence experiments on A431 cells but not in its denatured form as shown by its absence of staining in immunoblots. The positive chronotropic effect in vitro was specifically blocked by both the antigenic peptide and the specific beta2-antagonist (+/-)-1-[2,3-(Dihydro-7-methyl1H-inden-4-yl)oxy]-3-[(1-methy lethyl)amino]-2-butanol hydrochloride (ICI1118,551). This activity was mediated through activation of Ca2+ L-type channels as assessed in guinea pig cardiomyocytes. These results suggest that the epitope is located in an extracellular alpha-helix, whose recognition by the antibody could stabilize the receptor in its 'active' conformation.
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- 1998
7. In Vivoandin VitroInhibition of theL-type Calcium Current in Isolated Guinea-pig Cardiomyocytes by the Immunosuppressive Agent Cyclosporin A
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J Argibay, N. Peineau, Alfredo Mijares, and Claire O. Malécot
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Male ,Patch-Clamp Techniques ,Calcium Channels, L-Type ,Guinea Pigs ,Gating ,Pharmacology ,Guinea pig ,Subcutaneous injection ,In vivo ,Cyclosporin a ,Animals ,Patch clamp ,Phosphorylation ,Molecular Biology ,Ion Transport ,Chemistry ,Calcium channel ,Isoproterenol ,Adrenergic beta-Agonists ,In vitro ,Depression, Chemical ,Anesthesia ,Cyclosporine ,Calcium ,Calcium Channels ,Receptors, Adrenergic, beta-1 ,Cardiology and Cardiovascular Medicine ,Ion Channel Gating ,Protein Processing, Post-Translational ,Immunosuppressive Agents - Abstract
Cyclosporin A (CsA), an immunosuppressive agent used to reduce rejection after organ transplantation, induces secondary effects in heart tissue. We have studied the effects in vivo and in vitro of CsA on l -type Ca 2+ current (I Ca ) and the associated gating currents of isolated guinea-pig ventricular myocytes using the whole-cell patch-clamp technique. For in vivo experiments, a group of animals ( n =28) was treated for 21 days by subcutaneous injection of CsA (15 mg/kg/day). Blood level of CsA was 1191±221 ng/ml ( n =9). In cells from these animals ( n =65, 19 animals), I Ca was reduced to about 75% of that recorded from control cells ( n =32, six animals). CsA decreased the availability of Ca 2+ channels at potentials more positive than +30 mV. Isoproterenol (100 n m ) was still able to increase I Ca but only by 30±6% ( n =9), whereas in control it increased I Ca by 290±22% ( n =5). Gating currents related to l -type Ca 2+ channels were not altered in cells from CsA-treated animals. In in vitro experiments, CsA reduced I Ca when applied directly to cardiomyocytes. CsA affected the kinetics of I Ca inactivation, slowing down the rapid phase and accelerating the slow phase ( n =4). The steady-state inactivation curve of I Ca was shifted to more negative voltages and the degree of availability at −80 mV decreased by in vitro application of CsA. The half inactivation potential (V 1/2 ) changed from −23±0.6 mV in control to −31±2 mV, −48±0.6 mV and −49±0.6 mV, in 1, 50 and 80 μ m CsA, respectively. In these cells, the gating currents related to l -type Ca 2+ channels were also not altered by CsA. CsA does not modify the Ca 2+ channel density, although it induces a decrease in the β 1 -adrenergic stimulation of I Ca . The results are explained by a direct effect on the calcium channel inactivation of CsA and a non specific indirect effect.
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- 1997
8. Antibodies from Trypanosoma cruzi infected mice recognize the second extracellular loop of the ?1-adrenergic and M2-muscarinic receptors and regulate calcium channels in isolated cardiomyocytes
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Alfredo A. Mijares, Jorge J. Argibay, Bernard Vray, N. Peineau, Ludovic L. Verdot, and Johan Hoebeke
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Male ,medicine.medical_specialty ,Patch-Clamp Techniques ,Protein Conformation ,Trypanosoma cruzi ,Guinea Pigs ,Clinical Biochemistry ,Antibodies, Protozoan ,Biology ,Immunoenzyme Techniques ,Epitopes ,Mice ,Structure-Activity Relationship ,Internal medicine ,Muscarinic acetylcholine receptor M5 ,Muscarinic acetylcholine receptor ,Cyclic AMP ,medicine ,Animals ,Chagas Disease ,Patch clamp ,Receptor ,Molecular Biology ,Autoantibodies ,Mice, Inbred BALB C ,Receptor, Muscarinic M2 ,Voltage-dependent calcium channel ,Myocardium ,Muscarinic acetylcholine receptor M3 ,Heart ,Muscarinic acetylcholine receptor M2 ,Cell Biology ,General Medicine ,Muscarinic acetylcholine receptor M1 ,Propranolol ,Receptors, Muscarinic ,Molecular biology ,Electrophysiology ,Endocrinology ,Calcium Channels ,Receptors, Adrenergic, beta-1 - Abstract
Sera from T. cruzi infected mice were tested in an enzyme immunoassay on peptides corresponding to the second extracellular loops of the beta 1-, the beta 2-adrenergic receptor and the M2 muscarinic receptor. All sera of mice (4/4) in the acute phase recognized the beta 1-adrenergic receptor and the M2 muscarinic receptor peptides but not the beta 2-adrenergic receptor peptide. The same peptides were recognized during the chronic phase in half of the mice (6/12). The immunoglobulin fractions of the mice were tested for their activity on L-type Ca++ channels of isolated guinea-pig cardiomyocytes using the whole-cell patch clamp technique. The immunoglobulin fractions of acute phase mice were able to activate the Ca++ channels by stimulation of the beta-adrenergic receptors, as assessed by inhibition with propranolol. Those of the chronic phase mice reduced the Ca++ current by stimulation of the muscarinic receptors, as assessed by inhibition with atropine. These results confirm the existence of functional epitopes on the second extracellular loops of both receptors. They suggest that, as in humans, the parasite is able to elicit functional autoantibodies against these epitopes. They give evidence that these autoantibodies mediate their physiological effects by modulating the cAMP activated Ca++ channels.
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- 1996
9. Effect of ryanodine on cardiac calcium current and calcium channel gating current
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J Argibay, Alain Lacampagne, and C. Caputo
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medicine.medical_specialty ,Calcium Channels, L-Type ,Guinea Pigs ,Biophysics ,chemistry.chemical_element ,Muscle Proteins ,Calcium ,In Vitro Techniques ,Ryanodine receptor 2 ,Biophysical Phenomena ,Membrane Potentials ,Internal medicine ,medicine ,Animals ,Muscle, Skeletal ,Voltage-dependent calcium channel ,Ryanodine receptor ,Ryanodine ,Calcium channel ,Myocardium ,T-type calcium channel ,Skeletal muscle ,Ryanodine Receptor Calcium Release Channel ,Myocardial Contraction ,Kinetics ,Sarcoplasmic Reticulum ,Endocrinology ,medicine.anatomical_structure ,chemistry ,Calcium Channels ,medicine.symptom ,Ion Channel Gating ,Muscle contraction ,Muscle Contraction ,Research Article - Abstract
The effects of 100 microM ryanodine on the L-type calcium channel were studied using the pacth-clamp technique in isolated guinea pig ventricular myocytes. The inactivation kinetics of the calcium current were slowed down in the presence of ryanodine in agreement with the blockade of the release of calcium from the sarcoplasmic reticulum by the drug. The I-V and steady-state inactivation curves of the calcium current were shifted to negative values by ryanodine. A similar shift was observed in the activation and inactivation curves of the intramembrane charge movement associated with the calcium channel. Due to this shift, ryanodine slightly reduced the maximal amount of displaced charge although it did not modify the transition from the inactivated to the activated state (i.e., charge movement repriming). This result is in notable contrast with that obtained in skeletal muscle, where it has been found that ryanodine interferes with charge movement repriming. These results provide additional evidence of the postulated differences between the architecture of the excitation-contraction coupling system in cardiac and skeletal muscle.
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- 1996
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10. The stretch-activated ion channel blocker gadolinium also blocks L-type calcium channels in isolated ventricular myocytes of the guinea-pig
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François Gannier, Jean-Yves Le Guennec, Alain Lacampagne, J Argibay, and D Garnier
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medicine.medical_specialty ,medicine.drug_class ,Heart Ventricles ,Gadolinium ,Guinea Pigs ,Biophysics ,chemistry.chemical_element ,Calcium channel blocker ,In Vitro Techniques ,Biochemistry ,Membrane Potentials ,Guinea pig ,Internal medicine ,medicine ,Animals ,Ventricular Function ,L-type calcium channel ,EC50 ,Membrane potential ,Chemistry ,Biological activity ,Cell Biology ,Calcium Channel Blockers ,Biomechanical Phenomena ,Stretch-activated ion channel ,Endocrinology ,lipids (amino acids, peptides, and proteins) ,Cadmium - Abstract
We show that gadolinium (Gd3+) is a potent calcium channel blocker in guinea-pig isolated ventricular myocytes. A dose-dependent inhibition of ICaL was found with an EC50 of 1.4 microM and a complete inhibition at 10 microM Gd3+. When compared with Cd2+, it appeared that the blockade of ICaL is a complex phenomenon probably involving more than one site of interaction (a Hill coefficient of 1.6 was found for Gd3+ vs. 1.0 for Cd2+). It is concluded that Gd3+ ions completely block ICaL at concentrations used to block stretch-activated channels (SAC), rendering its use as a specific SAC inhibitor problematic.
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- 1994
11. The effects of increasing cell length on auxotonic contractions; membrane potential and intracellular calcium transients in single guinea-pig ventricular myocytes
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JY Le Guennec, D Garnier, JM Nigretto, François Gannier, J Argibay, and E S White
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medicine.medical_specialty ,Heart Ventricles ,Guinea Pigs ,chemistry.chemical_element ,In Vitro Techniques ,Calcium ,Sarcomere ,Calcium in biology ,Membrane Potentials ,Internal medicine ,medicine ,Animals ,Myocyte ,Membrane potential ,Chemistry ,Myocardium ,Cardiac muscle ,Arrhythmias, Cardiac ,General Medicine ,Myocardial Contraction ,Electric Stimulation ,Electrophysiology ,medicine.anatomical_structure ,Endocrinology ,Biophysics ,Stress, Mechanical ,Intracellular - Abstract
Until recently the investigation of length-dependent effects in cardiac muscle was restricted to multicellular preparations. We describe our experimental set-up which for the first time, in single cardiac myocytes, permits the effects of changes in cell length on auxotonic contractions (measured by carbon fibre transducers) to be simultaneously recorded with the effects on membrane potential and/or changes in intracellular calcium concentration (using indo-1 AM, acetoxylmethyl form). Consistent with previous findings (in experiments at 20-25 degrees C and 0.25 Hz) we report that following a stretch there was an increase in passive tension and contraction. A stretch which increased sarcomere length by approximately 3% had no significant effect on resting membrane potential or action potential amplitude. There was, however, a significant decrease in the action potential duration (P < 0.01, n = 8). No significant change in the amplitude of the intracellular calcium transient was seen following a stretch but a reduction in its duration was observed (P < 0.025, n = 11). Our observations on intracellular calcium transients are consistent with the hypothesis that, in mechanically loaded preparations, their time course is more dependent on changes in tension than changes in length.
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- 1993
12. 5-HT4 and 5-HT2 receptors antagonistically influence gap junctional coupling between rat auricular myocytes
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Norah Defamie, J Argibay, Nicolas Peineau, Jean-Claude Hervé, Mickaël Derangeon, Véronique Bozon, Denis Sarrouilhe, Nicolas Bourmeyster, Institut de physiologie et biologie cellulaires (IPBC), Université de Poitiers-Centre National de la Recherche Scientifique (CNRS), Signalisation et Transports Ioniques Membranaires (STIM), Université de Poitiers-Université de Tours-Centre National de la Recherche Scientifique (CNRS), and CNRS UMR 6542, Faculté des Sciences, Université de Tours, France.
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Serotonin 5-HT4 Receptor Antagonists ,Indoles ,Patch-Clamp Techniques ,Gap junction ,MESH: Gap Junctions ,MESH: Sulfonamides ,Connexin ,MESH: Myocytes, Cardiac ,Connexins ,MESH: Animals, Newborn ,MESH: Serotonin Antagonists ,0302 clinical medicine ,Serotonin Agents ,Piperidines ,MESH: Reverse Transcriptase Polymerase Chain Reaction ,Receptor, Serotonin, 5-HT2B ,[SDV.BC.IC]Life Sciences [q-bio]/Cellular Biology/Cell Behavior [q-bio.CB] ,Serotonin 5-HT2 Receptor Antagonists ,Receptor, Serotonin, 5-HT2C ,para-Aminobenzoates ,Myocyte ,5-HT2A ,Aminobenzoates ,Myocytes, Cardiac ,Receptor, Serotonin, 5-HT2A ,5-HT2B ,MESH: Animals ,Phosphorylation ,Receptor ,MESH: Serotonin Agents ,Cells, Cultured ,Cardiomyocytes ,MESH: Indoles ,0303 health sciences ,Sulfonamides ,Reverse Transcriptase Polymerase Chain Reaction ,Gap Junctions ,Cx40 ,MESH: Aminobenzoic Acids ,[SDV.MHEP.EM]Life Sciences [q-bio]/Human health and pathology/Endocrinology and metabolism ,musculoskeletal system ,Cx45 ,Cx43 ,MESH: Piperidines ,MESH: Serotonin 5-HT2 Receptor Antagonists ,Serotonin Antagonists ,Cardiology and Cardiovascular Medicine ,Adenylyl Cyclases ,MESH: Cells, Cultured ,medicine.medical_specialty ,Serotonin ,MESH: Rats ,Blotting, Western ,MESH: Receptors, Serotonin, 5-HT4 ,Biology ,In Vitro Techniques ,Serotonergic ,03 medical and health sciences ,Syncytial properties ,[SDV.MHEP.CSC]Life Sciences [q-bio]/Human health and pathology/Cardiology and cardiovascular system ,Internal medicine ,cAMP ,MESH: Adenylate Cyclase ,MESH: Patch-Clamp Techniques ,medicine ,Animals ,MESH: Blotting, Western ,Patch clamp ,Heart Atria ,Rats, Wistar ,Molecular Biology ,030304 developmental biology ,MESH: Phosphorylation ,MESH: Receptor, Serotonin, 5-HT2C ,MESH: Receptor, Serotonin, 5-HT2A ,MESH: Receptor, Serotonin, 5-HT2B ,[SDV.BBM.BM]Life Sciences [q-bio]/Biochemistry, Molecular Biology/Molecular biology ,MESH: Rats, Wistar ,Calcium current ,Rats ,MESH: Connexins ,Endocrinology ,Animals, Newborn ,MESH: Serotonin ,MESH: Serotonin 5-HT4 Receptor Antagonists ,MESH: Heart Atria ,Receptors, Serotonin, 5-HT4 ,030217 neurology & neurosurgery ,5-HT4a ,5-HT4b - Abstract
IF : 4,96; International audience; 5-hydroxytryptamine-4 (5-HT(4)) receptors have been proposed to contribute to the generation of atrial fibrillation in human atrial myocytes, but it is unclear if these receptors are present in the hearts of small laboratory animals (e.g. rat). In this study, we examined presence and functionality of 5-HT(4) receptors in auricular myocytes of newborn rats and their possible involvement in regulation of gap junctional intercellular communication (GJIC, responsible for the cell-to-cell propagation of the cardiac excitation). Western-blotting assays showed that 5-HT(4) receptors were present and real-time RT-PCR analysis revealed that 5-HT(4b) was the predominant isoform. Serotonin (1 microM) significantly reduced cAMP concentration unless a selective 5-HT(4) inhibitor (GR113808 or ML10375, both 1 microM) was present. Serotonin also reduced the amplitude of L-type calcium currents and influenced the strength of GJIC without modifying the phosphorylation profiles of the different channel-forming proteins or connexins (Cxs), namely Cx40, Cx43 and Cx45. GJIC was markedly increased when serotonin exposure occurred in presence of a 5-HT(4) inhibitor but strongly reduced when 5-HT(2A) and 5-HT(2B) receptors were inhibited, showing that activation of these receptors antagonistically regulated GJIC. The serotoninergic response was completely abolished when 5-HT(4), 5-HT(2A) and 5-HT(2B) were simultaneously inhibited. A 24 h serotonin exposure strongly reduced Cx40 expression whereas Cx45 was less affected and Cx43 still less. In conclusion, this study revealed that 5-HT(4) (mainly 5-HT(4b)), 5-HT(2A) and 5-HT(2B) receptors coexisted in auricular myocytes of newborn rat, that 5-HT(4) activation reduced cAMP concentration, I(Ca)(L) and intercellular coupling whereas 5-HT(2A) or 5-HT(2B) activation conversely enhanced GJIC.
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- 2010
13. Alteration of the L-type calcium current in guinea-pig single ventricular myocytes by heptaminol hydrochloride
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K.G. Mongo, J Argibay, J.-Y. Le Guennec, N. Peineau, and D Garnier
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medicine.medical_specialty ,Guinea Pigs ,chemistry.chemical_element ,In Vitro Techniques ,Calcium ,Membrane Potentials ,Internal medicine ,medicine ,Animals ,Myocyte ,Patch clamp ,Pharmacology ,Membrane potential ,Myocardium ,Heptaminol ,Electric Conductivity ,Heart ,Electrophysiology ,Endocrinology ,chemistry ,Steady state (chemistry) ,Perfusion ,Research Article ,medicine.drug - Abstract
1. The effects of heptaminol on calcium current amplitude and characteristics were studied in single ventricular myocytes of guinea-pig by use of the whole cell configuration of the patch clamp technique. 2. A concentration-dependent decrease in ICa amplitude was observed. At heptaminol concentration as low as 10(-6) M, this effect was observed in only two cells (n = 6). At 10(-5) M the reduction of ICa was of 30 +/- 15% (n = 11). 3. The current recovery from inactivation at -40 mV holding potential (HP) seemed less sensitive to perfusion with heptaminol (greater than 10(-6) M). However, at -80 mV HP the overshoot of the recovery curve was decreased by heptaminol. 4. Both at -40 mV and -80 mV HP, heptaminol (10(-5) M) significantly increased the steady state inactivation of ICa. 5. As previously proposed by others to explain the effects of membrane active substances, the effects of heptaminol may result from alterations in cell membrane properties and possibly from an increase in intracellular free calcium ion concentration.
- Published
- 1992
14. Stretch-induced increase of resting intracellular calcium concentration in single guinea-pig ventricular myocytes
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JY Le Guennec, François Gannier, J Argibay, Ed White, and D Garnier
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Sarcomeres ,Indoles ,Chemistry ,Myocardium ,Guinea Pigs ,Cardiac muscle ,General Medicine ,Myocardial Contraction ,Sarcomere ,Fluorescence ,Calcium in biology ,Guinea pig ,Resting Cell ,Cytosol ,medicine.anatomical_structure ,Biochemistry ,medicine ,Biophysics ,Animals ,Calcium ,Ventricular myocytes - Abstract
Single guinea-pig ventricular myocytes were loaded with the fluorescent Ca2+ indicator Indo-1 AM and stretched by carbon fibres. Stretching increased resting tension. Sarcomere lengths were increased by 2-18%. It was observed that a stretch increased resting [Ca2+]i in seven out of eight cells. The change in [Ca2+]i increased with the size of the stretch and returned to pre-stretch levels on return to resting cell length. These observations suggest a means by which changes in resting muscle length can modify the contractile state of cardiac muscle.
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- 1991
15. Conformational state of human cardiac 5-HT4(g) receptors influences the functional effects of polyclonal anti-5-HT4 receptor antibodies
- Author
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Emmanuella Di Scala, Véronique Bozon, Pierre Cosnay, J Argibay, Olivier Herault, S Rose, Communications, Médiations, Organisations, Savoirs ( CIMEOS ), Université de Bourgogne ( UB ), CNRS UMR 6542, Faculté des Sciences, Université de Tours, France., Hôpital Bretonneau, and Centre Hospitalier Régional Universitaire de Tours (CHRU Tours)
- Subjects
Protein Conformation ,conformational state ,Immune receptor ,Biology ,Biochemistry ,Antibodies ,03 medical and health sciences ,Cricetulus ,Antibody Specificity ,Cricetinae ,antibody ,Animals ,Humans ,Protease-activated receptor ,5-HT4 receptor ,Receptor ,5-HT receptor ,ComputingMilieux_MISCELLANEOUS ,030304 developmental biology ,G protein-coupled receptor ,Pharmacology ,0303 health sciences ,G protein-coupled receptor kinase ,[ SDV ] Life Sciences [q-bio] ,Myocardium ,030302 biochemistry & molecular biology ,CHO cells ,[SDV.MHEP.EM]Life Sciences [q-bio]/Human health and pathology/Endocrinology and metabolism ,musculoskeletal system ,Molecular biology ,inverse-agonist ,serotonin ,Metabotropic receptor ,5-HT1 receptor ,Receptors, Serotonin, 5-HT4 - Abstract
International audience; The functional effects of the anti-G21V antibody directed against the second extracellular loop of human heart S-HT4 receptors can differ when the receptors are expressed in different cell lines. Here, we extend these studies to show variation in the responses of 5-HT4(g) receptors to the antibody within the same expression system. In a previous report no effect of the anti-G21V antibodies had been shown upon 5-HT4(g) receptors expressed in CHO cells. Here the same antibodies alone or when added before 5-HT had a functional "inverse-agonist like" effect upon 5-HT4(g) receptors expressed in a separate line of CHO cells. Although these CHO cells showed a lower efficacy of cAMP production evoked by 5-HT than the previous report they express a similar hS-HT4(g) receptor density. Inhibition of either phosphodiesterases or Gi proteins had no effect upon the action of the antibody. Conformational states of the 5-HT4 receptor and/or equilibrium between different states of receptors may then determine the functional effect of antibodies against this receptor. (c) 2006 Elsevier Inc. All rights reserved.
- Published
- 2007
16. High Efficiency Activation of L-Type Ca 2+ Current by 5-HT in Human Atrial Myocytes
- Author
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Véronique Bozon, Pierre Cosnay, Ian Findlay, Emmanuella Di Scala, Michel Aupart, S Rose, J Argibay, CNRS UMR 6542, Faculté des Sciences, Université de Tours, France., CHU Trousseau [Tours], and Centre Hospitalier Régional Universitaire de Tours (CHRU Tours)
- Subjects
Male ,Time Factors ,Clinical Biochemistry ,Stimulation ,030204 cardiovascular system & hematology ,chemistry.chemical_compound ,0302 clinical medicine ,Endocrinology ,Ca current ,Cyclic AMP ,Myocyte ,atrial fibrillation ,Cells, Cultured ,Aged, 80 and over ,0303 health sciences ,Forskolin ,Voltage-dependent calcium channel ,Middle Aged ,[SDV.MHEP.EM]Life Sciences [q-bio]/Human health and pathology/Endocrinology and metabolism ,serotonin ,Electrophysiology ,Female ,medicine.symptom ,Adult ,medicine.medical_specialty ,Calcium Channels, L-Type ,human atrial myocytes ,Adrenergic beta-Antagonists ,Context (language use) ,03 medical and health sciences ,Internal medicine ,cAMP ,medicine ,Humans ,Heart Atria ,5-HT receptor ,Aged ,030304 developmental biology ,Pharmacology ,Muscle Cells ,Dose-Response Relationship, Drug ,Myocardium ,Colforsin ,Isoproterenol ,Cell Biology ,Mechanism of action ,chemistry ,Calcium ,Serotonin - Abstract
International audience; In human atrial myocytes, serotonin rather than sympathetic, stimulation is more frequently associated with atrial fibrillation. So does the arrhythmogenic effect of serotonin result from the mechanism of action of the receptor or the context of its action upon cardiac myocytes? The capacity of agonists to produce cAMP followed the sequence 5-HT < Iso < Forskolin to increase ICaL with 5-HT = Iso = Forskolin. The simultaneous application of threshold concentrations of 5-HT and Iso maximally increased ICaL. We will show that the effect of 5-HT upon human atrial myocytes is an imbalance between low production of cAMP and maximal activation of ICaL.
- Published
- 2004
17. Polyclonal antibody effects on the human cardiac 5-HT4(e) receptors depend upon the expression system
- Author
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Di Scala , Emmanuella, S. , Rose, O. , Hérault, J. , Argibay, P. , Cosnay, V. , Bozon, Communications, Médiations, Organisations, Savoirs ( CIMEOS ), and Université de Bourgogne ( UB )
- Subjects
[ SDV ] Life Sciences [q-bio] ,ComputingMilieux_MISCELLANEOUS - Abstract
International audience
- Published
- 2004
18. High efficiency activation of L-type Ca2+ current by 5-HT in human atrial myocytes
- Author
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Di Scala , Emmanuella, I. , Findlay, S. , Rose, M. , Aupart, J. , Argibay, P. , Cosnay, V. , Bozon, Communications, Médiations, Organisations, Savoirs ( CIMEOS ), and Université de Bourgogne ( UB )
- Subjects
[ SDV ] Life Sciences [q-bio] ,ComputingMilieux_MISCELLANEOUS - Abstract
International audience
- Published
- 2004
19. Presence of auto-antibodies directed against cardiac 5-HT4 receptor in sera of patients with atrial fibrillation
- Author
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Di Scala, Emmanuella, S., Rose, D., Gennetay, M., Pingaud, P., Cosnay, J., Argibay, Bozon, Véronique, Di Scala, Emmanuella, Communications, Médiations, Organisations, Savoirs (CIMEOS), Université de Bourgogne (UB), Communications, Médiations, Organisations, Savoirs ( CIMEOS ), and Université de Bourgogne ( UB )
- Subjects
[SDV] Life Sciences [q-bio] ,[ SDV ] Life Sciences [q-bio] ,[SDV]Life Sciences [q-bio] ,ComputingMilieux_MISCELLANEOUS - Abstract
National audience
- Published
- 2004
20. Effects of the polyclonal antibody anti-G21V on the cardiac h-5-HT4(e) receptors expressed in CHO cells depends upon receptor density
- Author
-
Di Scala , Emmanuella, S. , Rose, D. , Gennetay, M. , Pingaud, J. , Argibay, P. , Cosnay, V. , Bozon, Communications, Médiations, Organisations, Savoirs ( CIMEOS ), Université de Bourgogne ( UB ), Di Scala, Emmanuella, Communications, Médiations, Organisations, Savoirs (CIMEOS), and Université de Bourgogne (UB)
- Subjects
[SDV] Life Sciences [q-bio] ,[ SDV ] Life Sciences [q-bio] ,[SDV]Life Sciences [q-bio] ,ComputingMilieux_MISCELLANEOUS - Abstract
National audience
- Published
- 2003
21. Etude du récepteur h5-HT4(e)
- Author
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Di Scala, Emmanuella, S., Rose, D., Gennetay, M., Pingaud, J., Argibay, P., Cosnay, Bozon, Véronique, Communications, Médiations, Organisations, Savoirs ( CIMEOS ), Université de Bourgogne ( UB ), Di Scala, Emmanuella, Communications, Médiations, Organisations, Savoirs (CIMEOS), and Université de Bourgogne (UB)
- Subjects
[SDV] Life Sciences [q-bio] ,[ SDV ] Life Sciences [q-bio] ,[SDV]Life Sciences [q-bio] ,ComputingMilieux_MISCELLANEOUS - Abstract
National audience
- Published
- 2003
22. Activity of antibodies directed against the second extracellular loop of human cardiac h5-HT4(e) receptor according to the density of receptors expressed
- Author
-
Di Scala, Emmanuella, S., Rose, D., Gennetay, M., Pingaud, J., Argibay, P., Cosnay, Bozon, Véronique, Di Scala, Emmanuella, Communications, Médiations, Organisations, Savoirs ( CIMEOS ), Université de Bourgogne ( UB ), Communications, Médiations, Organisations, Savoirs (CIMEOS), and Université de Bourgogne (UB)
- Subjects
[SDV] Life Sciences [q-bio] ,[ SDV ] Life Sciences [q-bio] ,[SDV]Life Sciences [q-bio] ,ComputingMilieux_MISCELLANEOUS - Abstract
International audience
- Published
- 2003
23. Antagonist-like activity of antibodies against the cardiac h5-HT4 receptor
- Author
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Di Scala, Emmanuella, J., Argibay, P., Cosnay, Bozon, Véronique, Communications, Médiations, Organisations, Savoirs ( CIMEOS ), Université de Bourgogne ( UB ), Di Scala, Emmanuella, Communications, Médiations, Organisations, Savoirs (CIMEOS), and Université de Bourgogne (UB)
- Subjects
[SDV] Life Sciences [q-bio] ,[ SDV ] Life Sciences [q-bio] ,[SDV]Life Sciences [q-bio] ,ComputingMilieux_MISCELLANEOUS - Abstract
International audience
- Published
- 2002
24. Agonist-Like Activity of Antibodies Directed Against the Second Extracellular Loop of the Human Cardiac Serotonin 5-HT 4(e) Receptor in Transfected COS-7 Cells
- Author
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Rodolphe Fischmeister, E. Di Scala, Johan Hoebeke, Frank Lezoualc'h, J Argibay, Pierre Eftekhari, V. Bozon, CNRS UMR 6542, Faculté des Sciences, Université de Tours, France., FORENAP FRP, Forenap, Immunologie et chimie thérapeutiques (ICT), Cancéropôle du Grand Est-Centre National de la Recherche Scientifique (CNRS), Cardiologie cellulaire et moléculaire, and Institut National de la Santé et de la Recherche Médicale (INSERM)
- Subjects
Agonist ,[SDV.SA]Life Sciences [q-bio]/Agricultural sciences ,medicine.drug_class ,agonist-like ,Clinical Biochemistry ,Biology ,03 medical and health sciences ,Endocrinology ,cAMP ,Enzyme-linked receptor ,Extracellular ,medicine ,5-HT5A receptor ,atrial fibrillation ,5-HT4 receptor ,Receptor ,030304 developmental biology ,Pharmacology ,anti-peptide antibody ,0303 health sciences ,030302 biochemistry & molecular biology ,Cell Biology ,Transfection ,Ligand (biochemistry) ,Molecular biology ,COS-7 cells ,3. Good health ,Serotonin - Abstract
International audience; We have previously reported that antipeptide antibodies directed against the second extracellular loop of the cardiac h5-HT4 receptor could block the activation of the L-type Ca channel in human atrial cardiomyocytes. In this paper we investigate the immunological and physiological activity of these antibodies, in a cell system expressing a larger amount of receptors than the atrial cells. The recombinant receptor was expressed at the surface of COS-7 cells under an active form (serotonin, EC50 = 1.81 x 10(-7) M), at a high level (375 +/- 25 fmol receptor/mg total protein) and was able to bind a specific ligand (GR113808) with a high affinity (Kd = 0.28 +/- 0.05 nM). In this system, the same anti-peptide antibodies used for the cardiac cells induced an "agonist-like" effect on the recombinant h5-HT4 receptor. These results are in line with those shown for others G-protein coupled receptors, as adrenoreceptors. In addition, this work showed that the effect of the antibodies is not only dependent on the epitopic region recognised but also on the molecular density and/or the cellular environment of the target receptors. Finally, our results support the hypothesis that the h5-HT4 receptor could be a new target for autoantibodies in patients with atrial arrhythmia.
- Published
- 2002
25. Autoantibody effects on the cardiac recombinant human serotonin 4 receptor, h5-HT4(e)
- Author
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Di Scala , Emmanuella, S. , Rose, M. , Pingaud, P. , Cosnay, J. , Argibay, V. , Bozon, Di Scala, Emmanuella, Communications, Médiations, Organisations, Savoirs (CIMEOS), Université de Bourgogne (UB), Communications, Médiations, Organisations, Savoirs ( CIMEOS ), and Université de Bourgogne ( UB )
- Subjects
[SDV] Life Sciences [q-bio] ,[ SDV ] Life Sciences [q-bio] ,[SDV]Life Sciences [q-bio] ,ComputingMilieux_MISCELLANEOUS - Abstract
National audience
- Published
- 2002
26. Effects of autoantibodies on the cardiac recombinant human serotonin receptor h5 HT4(e)
- Author
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Di Scala , Emmanuella, D. , Gennetay, Rose , S., J. , Argibay, P. , Cosnay, V. , Bozon, Di Scala, Emmanuella, Communications, Médiations, Organisations, Savoirs (CIMEOS), Université de Bourgogne (UB), Communications, Médiations, Organisations, Savoirs ( CIMEOS ), and Université de Bourgogne ( UB )
- Subjects
[SDV] Life Sciences [q-bio] ,[ SDV ] Life Sciences [q-bio] ,[SDV]Life Sciences [q-bio] ,ComputingMilieux_MISCELLANEOUS - Abstract
National audience
- Published
- 2002
27. Agonist-like activity of antibodies directed against the second extracellular loop of the human cardiac serotonin 5-HT4(e) receptor in transfected COS-7 cells
- Author
-
V. , Bozon, Di Scala , Emmanuella, P. , Eftekhari, J. , Hoebeke, R. , Fischmeister, F. , Lezoualc’h, J. , Argibay, Communications, Médiations, Organisations, Savoirs ( CIMEOS ), and Université de Bourgogne ( UB )
- Subjects
[ SDV ] Life Sciences [q-bio] ,Myocardium ,In Vitro Techniques ,Transfection ,Recombinant Proteins ,Enzyme Activation ,Epitopes ,Antibody Specificity ,Receptors, Serotonin ,Atrial Fibrillation ,COS Cells ,Animals ,Humans ,Receptors, Serotonin, 5-HT4 ,ComputingMilieux_MISCELLANEOUS ,Adenylyl Cyclases ,Autoantibodies - Abstract
We have previously reported that antipeptide antibodies directed against the second extracellular loop of the cardiac h5-HT4 receptor could block the activation of the L-type Ca channel in human atrial cardiomyocytes. In this paper we investigate the immunological and physiological activity of these antibodies, in a cell system expressing a larger amount of receptors than the atrial cells. The recombinant receptor was expressed at the surface of COS-7 cells under an active form (serotonin, EC50 = 1.81 x 10(-7) M), at a high level (375 +/- 25 fmol receptor/mg total protein) and was able to bind a specific ligand (GR113808) with a high affinity (Kd = 0.28 +/- 0.05 nM). In this system, the same anti-peptide antibodies used for the cardiac cells induced an "agonist-like" effect on the recombinant h5-HT4 receptor. These results are in line with those shown for others G-protein coupled receptors, as adrenoreceptors. In addition, this work showed that the effect of the antibodies is not only dependent on the epitopic region recognised but also on the molecular density and/or the cellular environment of the target receptors. Finally, our results support the hypothesis that the h5-HT4 receptor could be a new target for autoantibodies in patients with atrial arrhythmia.
- Published
- 2002
28. Immunological analyses of the cardiac h5-HT4(e) receptor
- Author
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Di Scala , Emmanuella, S. , Rose, D. , Gennetay, M. , Pingaud, J. , Argibay, P. , Cosnay, V. , Bozon, Di Scala, Emmanuella, Communications, Médiations, Organisations, Savoirs (CIMEOS), Université de Bourgogne (UB), Communications, Médiations, Organisations, Savoirs ( CIMEOS ), and Université de Bourgogne ( UB )
- Subjects
[SDV] Life Sciences [q-bio] ,[ SDV ] Life Sciences [q-bio] ,[SDV]Life Sciences [q-bio] ,ComputingMilieux_MISCELLANEOUS - Abstract
National audience
- Published
- 2002
29. Immunological and functional study of human recombinant serotonin 4 receptor, h5-HT4(e)
- Author
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Di Scala , Emmanuella, S. , Rose, D. , Gennetay, M. , Pingaud, J. , Argibay, P. , Cosnay, V. , Bozon, Communications, Médiations, Organisations, Savoirs (CIMEOS), Université de Bourgogne (UB), Communications, Médiations, Organisations, Savoirs ( CIMEOS ), Université de Bourgogne ( UB ), and Di Scala, Emmanuella
- Subjects
[SDV] Life Sciences [q-bio] ,[ SDV ] Life Sciences [q-bio] ,[SDV]Life Sciences [q-bio] ,ComputingMilieux_MISCELLANEOUS - Abstract
National audience
- Published
- 2001
30. Inhibitory activity of antibodies against the human atrial 5-HT(4)receptor
- Author
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Johan Hoebeke, J Argibay, Pierre Cosnay, Pierre Eftekhari, Laurent Sallé, and Michel Aupart
- Subjects
medicine.medical_specialty ,Serotonin ,Patch-Clamp Techniques ,Calcium Channels, L-Type ,Molecular Sequence Data ,CHO Cells ,Immunoenzyme Techniques ,Immunoglobulin Fab Fragments ,Internal medicine ,Cricetinae ,medicine ,Extracellular ,Animals ,Humans ,Patch clamp ,Amino Acid Sequence ,Heart Atria ,Receptor ,Molecular Biology ,5-HT receptor ,Cells, Cultured ,biology ,Chinese hamster ovary cell ,Calcium channel ,Atrial Function ,Calcium Channel Blockers ,Electrophysiology ,Endocrinology ,Receptors, Serotonin ,biology.protein ,Rabbits ,Receptors, Serotonin, 5-HT4 ,Antibody ,Cardiology and Cardiovascular Medicine ,Peptides - Abstract
Antibodies directed against the second extracellular loop of G protein-coupled receptors have been shown to exert "agonist-like" activities. In order to test the hypothesis that this is a general phenomenon, antibodies were raised in rabbits against a synthetic peptide corresponding to the second extracellular loop of the newly sequenced human cardiac 5-HT(4)receptor. The antibodies were affinity-purified and shown to recognize the 5-HT(4)receptor in immunoblots of Chinese hamster ovary (CHO) cells expressing the receptor. The antibodies had no intrinsic effect but could depress the activation of L -type calcium channel induced by serotonin in human atrial cells. This antagonist-like effect was exerted both by intact IgG and by Fab fragments. These results are physiologically important since it has been shown that the 5-HT(4)receptor could be a target for autoantibodies in mothers at risk of giving birth to children with neonatal atrio-ventricular block.
- Published
- 2001
31. Anti-SSA/Ro52 autoantibodies blocking the cardiac 5-HT4 serotoninergic receptor could explain neonatal lupus congenital heart block
- Author
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Frank Lezoualc'h, Johan Hoebeke, Jean-Paul Briand, David A. Isenberg, Monique Gastineau, Pierre Eftekhari, Jeanne Mialet, Laurent Sallé, J Argibay, Gilbert J. Fournié, Rodolphe Fischmeister, and Sylviane Muller
- Subjects
Male ,Anti-nuclear antibody ,Amino Acid Motifs ,Peptide ,Autoantigens ,Epitope ,Antibody Specificity ,Pregnancy ,Cricetinae ,RNA, Small Cytoplasmic ,Immunology and Allergy ,Lupus Erythematosus, Systemic ,Receptor ,Peptide sequence ,Ribonucleoprotein ,chemistry.chemical_classification ,Middle Aged ,musculoskeletal system ,Ribonucleoproteins ,Antibodies, Antinuclear ,Female ,Rabbits ,Ion Channel Gating ,Adult ,medicine.medical_specialty ,Recombinant Fusion Proteins ,Immunology ,Molecular Sequence Data ,CHO Cells ,Biology ,Cross Reactions ,Transfection ,Autoimmune Diseases ,Cricetulus ,Internal medicine ,medicine ,Animals ,Humans ,Amino Acid Sequence ,Aged ,Ion Transport ,Myocardium ,Autoantibody ,Infant, Newborn ,Peptide Fragments ,Pregnancy Complications ,Endocrinology ,Heart Block ,chemistry ,Receptors, Serotonin ,Calcium Channels ,Receptors, Serotonin, 5-HT4 ,Immunity, Maternally-Acquired ,Anti-SSA/Ro autoantibodies - Abstract
The 52-kDa SSA/Ro (Ro52) ribonucleoprotein is an antigenic target strongly associated with the autoimmune response in mothers whose children develop neonatal lupus and congenital heart block. When sera from patients with systemic lupus erythematosus were used as autoimmune controls in an enzyme immunoassay to screen for antibodies against the human serotoninergic 5-HT4-receptor, a high correlation was found between the presence of anti-Ro52 protein antibodies in such sera and antibodies reacting with a synthetic peptide, corresponding to the second extracellular loop of the human 5-HT4 receptor (amino acid residues 165-185). Homology scanning between the 5-HT4 peptide and the sequence of the Ro52 protein indicated two potential common epitopes located between residues 365 and 396 of the Ro52 protein. Cross-reactivity was found between the peptide derived from the 5-HT4 receptor, and a peptide corresponding to residues 365-382 of the Ro52 protein. Autoantibodies, affinity-purified on the 5-HT4 receptor peptide, specifically recognized both the Ro52 protein and the 5-HT4 receptor protein in immunoblots. The affinity-purified antibodies antagonized the serotonin-induced L-type Ca channel activation on human atrial cells. This effect could explain the electrophysiological abnormalities in neonatal lupus.
- Published
- 2000
32. Effect of sulfhydryl oxidation on ionic and gating currents associated with L-type calcium channels in isolated guinea-pig ventricular myocytes
- Author
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Alain Lacampagne, Anne Duittoz, J Argibay, N. Peineau, Pura Bolaños, Laboratoire de Physiologie des Cellules Cardiaques et Vasculaires (IPBC), Centre National de la Recherche Scientifique (CNRS), and Duittoz, Anne
- Subjects
Patch-Clamp Techniques ,MESH: Myocardium ,Physiology ,[SDV]Life Sciences [q-bio] ,Guinea Pigs ,chemistry.chemical_element ,Gating ,Calcium ,Dithiothreitol ,MESH: Guinea Pigs ,03 medical and health sciences ,chemistry.chemical_compound ,0302 clinical medicine ,BAPTA ,Physiology (medical) ,MESH: Oxidants ,MESH: Patch-Clamp Techniques ,Animals ,L-type calcium channel ,MESH: Animals ,Patch clamp ,[SDV.NEU] Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC] ,Sulfhydryl Compounds ,MESH: Sulfhydryl Compounds ,[SDV.BDLR] Life Sciences [q-bio]/Reproductive Biology ,Cells, Cultured ,030304 developmental biology ,0303 health sciences ,[SDV.BA.MVSA]Life Sciences [q-bio]/Animal biology/Veterinary medicine and animal Health ,Voltage-dependent calcium channel ,Chemistry ,Calcium channel ,Myocardium ,[SDV.BA.MVSA] Life Sciences [q-bio]/Animal biology/Veterinary medicine and animal Health ,[SDV.BDLR]Life Sciences [q-bio]/Reproductive Biology ,MESH: Ion Channel Gating ,Oxidants ,Phenylmercury Compounds ,[SDV] Life Sciences [q-bio] ,MESH: Phenylmercury Compounds ,Biochemistry ,Biophysics ,MESH: Calcium Channels ,[SDV.NEU]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC] ,Calcium Channels ,Cardiology and Cardiovascular Medicine ,Ion Channel Gating ,030217 neurology & neurosurgery ,MESH: Cells, Cultured - Abstract
Objective: L-type calcium currents (Ica) and gating currents modification by extracellular application of the selective free sulfhydryl oxidant p -hydroxy-mercuric-phenylsulphonic acid (PHMPS) were studied. Methods: Both currents were obtained with the whole cell patch clamp technique in guinea-pig ventricular cardiocytes. Results: The main finding was a reduction of Ica clearly differentiable from a “run down” process. This effect was protected, stopped and in some cases partially reversed by dithiothreitol, a protective reagent for -SH groups. We also found a decrease of the gating currents associated with L-type calcium channels. The calcium modulation and cAMP phosphorylation systems of Ica are unaffected by PHMPS. With barium as charge carrier the current-voltage curves of barium currents were shifted by 10 mV to the positive direction by PHMPS. The same effect was obtained with calcium currents using BAPTA as a fast calcium buffer. Conclusion: The results indicate that oxidation of -SH groups carried by the channel protein induces dysfunction of the calcium entry to cardiac cells by altering the gating process. A participation of thiol functions on the gating of the calcium channel is proposed.
- Published
- 1995
33. A simple method for calibrating collagenase/pronase E ratio to optimize heart cell isolation
- Author
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Frédéric Esnard, Alain Lacampagne, N. Peineau, François Gannier, Francis Gauthier, D Garnier, Jean-Yves Le Guennec, and J Argibay
- Subjects
Proteases ,Guinea Pigs ,Molecular Sequence Data ,chemistry.chemical_element ,Pronase ,Cell Separation ,Calcium ,Biology ,chemistry.chemical_compound ,medicine ,Animals ,Amino Acid Sequence ,Collagenases ,Sodium dodecyl sulfate ,Polyacrylamide gel electrophoresis ,Gel electrophoresis ,Myocardium ,Cell Biology ,General Medicine ,Biochemistry ,chemistry ,Calibration ,Collagenase ,Interstitial collagenase ,Electrophoresis, Polyacrylamide Gel ,medicine.drug - Abstract
A mixture of crude collagenase and non-specific proteases has been used to isolate guinea pig ventricular heart cells. Measurements of collagenase activity with Wunsch's substrate and protein content with sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) suggest that collagenase enzymes do not play a major role in heart cell isolation. On the other hand, an important factor in heart digestion seems to consist of some fractions of the proteases present in crude collagenase. It is also noted that crude collagenases do not present any sensitivity to added calcium but because this ion is important to obtain isolated cells its role is discussed. According to our results, the SDS-PAGE method can be used to determine the appropriate enzyme concentrations to obtain calcium-tolerant myocytes. These myocytes have electrophysiological properties as reported in the literature.
- Published
- 1993
34. Rate dependence of action potential duration and calcium current in isolated guinea-pig cardiocytes
- Author
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N. Peineau, J Argibay, and D Garnier
- Subjects
Voltage-dependent calcium channel ,Myocardium ,Guinea Pigs ,Electric Conductivity ,chemistry.chemical_element ,Action Potentials ,Heart ,General Medicine ,Cell Separation ,Intracellular Membranes ,Calcium ,Calcium in biology ,Electric Stimulation ,Guinea pig ,Cytosol ,EGTA ,chemistry.chemical_compound ,chemistry ,BAPTA ,Biophysics ,Reaction Time ,Action potential duration ,Animals - Abstract
The duration of the action potential at 50% of its amplitude (APD50) and peak calcium currents (ICa) was measured in single cardiac guinea-pig ventricular cells, using the whole-cell patch-clamp technique in current-clamp and voltage-clamp modes respectively. In the absence of intracellular calcium buffer, pacing at 0.28 Hz from a rest period of 1-2 min induced a transient increase (15.5 +/- 3.5%) in APD50, followed by a gradual shortening. Switching from 0.28 to 0.75 Hz again induced a transient increase of APD50 (6.8 +/- 2.9%). In the presence of EGTA or BAPTA on the cytosolic side of the membrane, this transient phase was prolonged and its amplitude slightly increased (10.6% when switching from 0.28 to 0.75 Hz in 5 mM-BAPA). The same increase in rate induced either a negative or a positive staircase of ICa, depending on the holding potential. At a holding potential of -80 mV, ICa peak was enhanced and the inactivation kinetics was slowed down. This facilitation of ICa seems to be dependent on calcium ions entering the cell via the calcium channels and could partly explain the observed transient increase in APD50.
- Published
- 1992
35. Differences in the hypoxic contraction of small isolated pulmonary arteries of cat and rabbit
- Author
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J Argibay, Pierre Bonnet, Ed White, and D Garnier
- Subjects
medicine.medical_specialty ,Contraction (grammar) ,Physiology ,Pulmonary Artery ,Biochemistry ,Procaine ,Norepinephrine ,Endocrinology ,Internal medicine ,medicine ,Animals ,Hypoxia ,Ecology, Evolution, Behavior and Systematics ,Lagomorpha ,biology ,Dose-Response Relationship, Drug ,Fissipedia ,Anatomy ,Hypoxia (medical) ,biology.organism_classification ,Oxygen ,Vasoconstriction ,Circulatory system ,Cats ,Animal Science and Zoology ,Rabbits ,medicine.symptom ,medicine.drug ,Muscle contraction ,Histamine - Abstract
In small (less than 300 microns diameter) pulmonary arterial (PA) rings isolated from the cat, hypoxia induced a transient contraction (250 +/- 120 mg, n = 7), whereas in rings of rabbit PA of the same size, hypoxia had no significant effect (n = 19). Precontraction by 40 mmol KCl.1(-1), noradrenaline (NA) 10(-6) mol.1(-1), or histamine (His 10(-5) mol.1(-1)) did not modify this difference between the two species and did not potentiate the hypoxic contraction of small rings of the cat PA. Large rabbit pulmonary arterial segments (300-2000 microns) exhibited no response to hypoxia before precontraction (n = 15). In the presence of procaine (2%) rabbit PA rings (n = 6, small) exhibited no hypoxic contraction. These results in vitro reflect previous in vivo observations.
- Published
- 1991
36. A new method of attachment of isolated mammalian ventricular myocytes for tension recording: length dependence of passive and active tension
- Author
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JY Le Guennec, N. Peineau, K.G. Mongo, J Argibay, and D Garnier
- Subjects
Myofilament ,Materials science ,Guinea Pigs ,In Vitro Techniques ,Sarcomere ,Cell membrane ,medicine ,Methods ,Animals ,Fiber ,Molecular Biology ,biology ,Tension (physics) ,Myocardium ,Models, Cardiovascular ,Anatomy ,Myocardial Contraction ,Biomechanical Phenomena ,medicine.anatomical_structure ,biology.protein ,Biophysics ,Titin ,medicine.symptom ,Cardiology and Cardiovascular Medicine ,Intracellular ,Muscle contraction - Abstract
The study of the Frank-Starling's law in mammalian single cells has been hindered by a lack of an easily performed method of stretching cells. Some authors have succeeded in this but their methods required a great deal of technical expertise and in most cases they have not had much success. We have developed an easy method of stretching mammalian ventricular cells from slack sarcomere length (S.L.) (Lo, 1.77 +/- 0.05 microns) to about 117% of this length. Thin carbon fibers (12 microns in diameter) which can be bound electrochemically to the cell membrane surface have been used. A flexible long fiber of known compliance (80 microns/microN) was attached to one end of the cell and a stiff double fiber (4 microns/microN) to the other end. The cell attachment was relatively easy to perform and successful results were obtained in 80% of the attempts. The displacement of the flexible fiber allows the quantitative measurements of the resting tension in a group of non-stimulated cells and of auxotonic contractions developed upon stimulation in another group of cells. Increasing S.L. from Lo to 105-106% of Lo, an increase in active tension from 0.21 +/- 0.03 mN/mm to 0.26 +/- 0.01 mN/mm (n = 4) could be noticed with a stimulation frequency of 0.5 Hz. An increase in active tension was also observed at 1 Hz. Staircase kinetics were accelerated with stretching; this confirms at the single cell level the hypothesis of an effect of length-dependent activation on the staircase. Eulerian differential stiffness constant was calculated and found to be 13.5 +/- 1.2, a value which is comparable to that described in intact heart. Thus the important stiffness found in the whole heart may be due to intracellular component(s) such as myofilament and/or connectin.
- Published
- 1990
37. Cardiac 5_HT4 receptor in children: functional and pharmacological characteristics
- Author
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E. Bergöend, Marchand M, J Argibay, M Pingaud, D Gennetay, Véronique Bozon, A. Tahir, Pierre Cosnay, A. Fitou, Michel Aupart, and P. Neville
- Subjects
business.industry ,Medicine ,Pharmacology ,Cardiology and Cardiovascular Medicine ,business ,Receptor ,Molecular Biology - Published
- 2006
38. Agonist like effects of an antipeptidic antibody (AC G21V) raised against the exoloop 2 on human cardiac recombinant 5-HT4 receptor activity
- Author
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J. Argibay and V. Bozon
- Subjects
Agonist ,biology ,law ,Chemistry ,medicine.drug_class ,Recombinant DNA ,medicine ,biology.protein ,5-HT4 receptor ,Pharmacology ,Antibody ,Biochemistry ,law.invention - Published
- 2000
39. Effects of a sulfhydryl reagent on L-type Ca current in guinea pig ventricular myocytes
- Author
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Alain Lacampagne, A.H. Duittoz, J Argibay, and D Garnier
- Subjects
Guinea pig ,medicine.medical_specialty ,Chemistry ,Internal medicine ,Sulfhydryl reagent ,Cardiology ,medicine ,Ventricular myocytes ,Pharmacology ,Current (fluid) ,Cardiology and Cardiovascular Medicine ,Molecular Biology - Published
- 1992
40. Effects of heptaminol on calcium current in guinea-pig ventricular myocytes
- Author
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JY Le Guennec, J Argibay, K.G. Mongo, N. Peineau, and D Garnier
- Subjects
Guinea pig ,Chemistry ,Heptaminol ,medicine ,Ventricular myocytes ,Calcium current ,Pharmacology ,Cardiology and Cardiovascular Medicine ,Molecular Biology ,medicine.drug - Published
- 1990
41. CONTRACTILE RESPONSES TO HYPOXIA OF ISOLATED RINGS FROM THE LEFT BRANCH OF RABBIT PULMONARY ARTERY
- Author
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D. Garnier, P. Bonnet, and J Argibay
- Subjects
Male ,medicine.medical_specialty ,Contraction (grammar) ,Endothelium ,Muscle Relaxation ,Arachidonic Acids ,In Vitro Techniques ,Pulmonary Artery ,Biology ,Muscle, Smooth, Vascular ,Potassium Chloride ,Norepinephrine ,medicine.artery ,Internal medicine ,medicine ,Animals ,Diethylcarbamazine ,Pharmacology (medical) ,Hypoxia ,Pharmacology ,Left pulmonary artery ,Acetylcholine ,medicine.anatomical_structure ,Muscle relaxation ,Endocrinology ,Anesthesia ,Pulmonary artery ,Circulatory system ,Endothelium, Vascular ,Rabbits ,medicine.symptom ,Vasoconstriction ,Muscle Contraction ,Blood vessel - Abstract
Contractile responses of left extrapulmonary artery segments with either intact or damaged endothelium were examined with changes in PO2 at constant pH. Hypoxia consistently reduced noradrenaline-induced contractions. This hypoxia-induced relaxation was sometimes followed by a contraction and a second relaxation. Hypoxia-induced relaxations were also obtained if precontraction was elicited with KCl (40 mM), but no triphasic response was observed. Relaxations faded away with time and only contractions were then observed. Relaxations were more considerable in rings from young animals and, although always present, decreased with the age of the animal. Endothelium damage reduced hypoxia-induced relaxations. Indomethacin, a potent blocker of cyclooxygenase, increased hypoxia-induced contraction and reduced relaxation in segments with intact endothelium. Without endothelium the indomethacin effect was less significant. It is concluded that the response to hypoxia of the pulmonary artery is similar to that of systemic vessels. Endothelium seems to play a modulatory role in the hypoxia-induced response in extrapulmonary artery. Prostaglandin metabolism seems to play a minor role in this modulation.
- Published
- 1989
42. Anti-peptide antibodies sensitive to the ‘active’ state of the β2-adrenergic receptor
- Author
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Alfredo Mijares, J Argibay, Diane Lebesgue, and Johan Hoebeke
- Subjects
Agonist ,β2-adrenergic receptor ,medicine.medical_specialty ,medicine.drug_class ,Molecular Sequence Data ,Biophysics ,Pharmacology ,Alpha-1B adrenergic receptor ,Biochemistry ,Antibodies ,Cell Line ,Beta-1 adrenergic receptor ,Mice ,chemistry.chemical_compound ,Structural Biology ,Internal medicine ,Genetics ,medicine ,Animals ,Humans ,Inverse agonist ,Amino Acid Sequence ,G protein-coupled receptor ,Zinterol ,Alpha-1D adrenergic receptor ,Molecular Biology ,Antibody ,Chemistry ,Conformer ,Cell Biology ,Alpha-1A adrenergic receptor ,Calcium current ,Endocrinology ,Competitive antagonist ,Peptide ,Receptors, Adrenergic, beta-2 ,Peptides - Abstract
Antibodies directed against a peptide corresponding to the second loop of the human beta2-adrenergic receptor were induced in rabbits by immunisation with the free peptide in complete Freund's adjuvant. The resulting antibodies were affinity-purified and shown to be monospecific for the target receptor. They were able to stimulate the L-type Ca2+ channels in whole-cell patch-clamp experiments on isolated adult guinea-pig cardiomyocytes. This effect was similar to that obtained by the specific beta2-adrenergic agonist zinterol. The antibody effects could be blocked with the specific beta2-adrenergic inverse agonist ICI118,551 but not with the neutral antagonist alprenolol. These results suggest that the antibodies recognise the active conformer of the beta2-adrenergic receptor.
- Full Text
- View/download PDF
43. Decrease in internal H+ and positive inotropic effect of heptaminol hydrochloride: a 31P n.m.r. spectroscopy study in rat isolated heart
- Author
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François Seguin, Alain Le Pape, Jean Philippe Grivet, D Garnier, Bernard Pourrias, J Argibay, and François Berthiau
- Subjects
Inotrope ,Male ,endocrine system ,Alkalosis ,Magnetic Resonance Spectroscopy ,Intracellular pH ,Coronary Disease ,Pharmacology ,In Vitro Techniques ,Phosphocreatine ,Contractility ,chemistry.chemical_compound ,medicine ,Animals ,Heptaminol ,Myocardium ,Sodium ,Heart ,Rats, Inbred Strains ,Hydrogen-Ion Concentration ,medicine.disease ,Amino Alcohols ,Myocardial Contraction ,Stimulation, Chemical ,Amiloride ,Rats ,Ion Exchange ,chemistry ,Biochemistry ,Ventricular pressure ,Potassium ,medicine.drug ,Research Article - Abstract
1. The cardiotonic effect of heptaminol hydrochloride (Hept-a-myl, Delalande) was studied using 31P-nuclear magnetic resonance (n.m.r.) spectroscopy and left ventricular pressure (LVP) measurements in rat isolated hearts. The possibility of this effect being mediated by an intracellular realkalinisation was tested. 2. Isolated hearts were perfused at 10 ml min-1 by the Langendorff method with Krebs-Henseleit solution at 37 degrees C and stimulated at 5 Hz. Mechanical activity was measured as variations of left ventricular pressure (LVP). 31P-n.m.r. spectra were recorded every 2 min. Changes in cardiac adenosine triphosphate (ATP), phosphocreatine (PCr) and inorganic phosphate (Pi) were followed and intracellular pH (pHi) was estimated from the chemical shift of Pi. 3. The effects of heptaminol were tested in different conditions: normoxia, moderate ischaemia, severe ischaemia, and moderate ischaemia in the presence of amiloride or guanidinium chloride as inhibitors of the Na-H exchange. 4. In normoxia, heptaminol induced a cyclic increase of systolic LVP, associated with an increase in Pi. No significant effect on pHi was observed. In changing from normoxia to moderate ischaemia, PCr and systolic LVP decreased; a mild intracellular acidification (pHi 6.96) was obtained. Heptaminol induced a restoration of pHi and increased LVP. In severe ischaemia, the realkalinization effect and the restoration of LVP induced by heptaminol were no longer observed. During moderate ischaemia, Na-H exchange inhibitors decreased pHi and LVP. Heptaminol applied in the presence of these inhibitors was unable to restore pHi and LVP. In severe ischaemia, the realkalinization effect and the restoration of LVP induced by heptaminol were no longer observed. During moderate ischaemia, Na-H exchange inhibitors decreased pHi and LVP. Heptaminol applied in the presence of these inhibitors was unable to restore pHi and LVP. 5. These results suggest that the positive inotropic effect of heptaminol during moderate ischaemia could be related to a restoration of internal pH, possibly mediated by a stimulation of the Na-H exchange.
- Published
- 1989
44. Conformational state of human cardiac 5-HT(4(g)) receptors influences the functional effects of polyclonal anti-5-HT(4) receptor antibodies.
- Author
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Di Scala E, Rose S, Hérault O, Argibay J, Cosnay P, and Bozon V
- Subjects
- Animals, CHO Cells, Cricetinae, Cricetulus, Humans, Receptors, Serotonin, 5-HT4 immunology, Antibodies immunology, Antibody Specificity immunology, Myocardium chemistry, Protein Conformation, Receptors, Serotonin, 5-HT4 chemistry
- Abstract
The functional effects of the anti-G21V antibody directed against the second extracellular loop of human heart 5-HT(4) receptors can differ when the receptors are expressed in different cell lines. Here, we extend these studies to show variation in the responses of 5-HT(4(g)) receptors to the antibody within the same expression system. In a previous report no effect of the anti-G21V antibodies had been shown upon 5-HT(4(g)) receptors expressed in CHO cells. Here the same antibodies alone or when added before 5-HT had a functional "inverse-agonist like" effect upon 5-HT(4(g)) receptors expressed in a separate line of CHO cells. Although these CHO cells showed a lower efficacy of cAMP production evoked by 5-HT than the previous report they express a similar h5-HT(4(g)) receptor density. Inhibition of either phosphodiesterases or Gi proteins had no effect upon the action of the antibody. Conformational states of the 5-HT(4) receptor and/or equilibrium between different states of receptors may then determine the functional effect of antibodies against this receptor.
- Published
- 2007
- Full Text
- View/download PDF
45. High efficiency activation of L-type Ca2+ current by 5-HT in human atrial myocytes.
- Author
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Di Scala E, Findlay I, Rose S, Aupart M, Argibay J, Cosnay P, and Bozon V
- Subjects
- Adrenergic beta-Antagonists pharmacology, Adult, Aged, Aged, 80 and over, Atrial Fibrillation, Calcium metabolism, Cells, Cultured, Colforsin chemistry, Cyclic AMP metabolism, Dose-Response Relationship, Drug, Electrophysiology, Female, Humans, Isoproterenol pharmacology, Male, Middle Aged, Muscle Cells metabolism, Myocardium pathology, Time Factors, Calcium Channels, L-Type metabolism, Heart Atria drug effects, Heart Atria pathology, Serotonin pharmacology
- Abstract
In human atrial myocytes, serotonin rather than sympathetic, stimulation is more frequently associated with atrial fibrillation. So does the arrhythmogenic effect of serotonin result from the mechanism of action of the receptor or the context of its action upon cardiac myocytes? The capacity of agonists to produce cAMP followed the sequence 5-HT < Iso < Forskolin to increase ICaL with 5-HT = Iso = Forskolin. The simultaneous application of threshold concentrations of 5-HT and Iso maximally increased ICaL. We will show that the effect of 5-HT upon human atrial myocytes is an imbalance between low production of cAMP and maximal activation of ICaL.
- Published
- 2004
- Full Text
- View/download PDF
46. Polyclonal antibody effects on the human cardiac 5-HT4(e) receptors depend upon the expression system.
- Author
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Di Scala E, Rose S, Hérault O, Argibay J, Cosnay P, and Bozon V
- Subjects
- Animals, CHO Cells, COS Cells, Chlorocebus aethiops, Cloning, Molecular, Cricetinae, Cricetulus, Flow Cytometry, Humans, Receptors, Serotonin, 5-HT4 genetics, Time Factors, Antibodies immunology, Myocardium immunology, Receptors, Serotonin, 5-HT4 immunology
- Abstract
The initial objective of this work was to examine the effects of an antibody (Anti-G21V) directed against the second extracellular loop of human heart 5-HT4 receptors expressed in Chinese hamster ovary (CHO) cells. The antibody anti-G21V had no effect upon either basal cAMP-or 5-HT-evoked increases in cAMP in CHO cells, whereas it had shown an agonist-like effect in COS-7 cells. Analysis of agonist fractions of h5-HT4(e) receptors in CHO and COS-7 cells revealed that equilibrium constant could underlie the different responses of the receptor toward the anti-G21V antibody. Therefore, different expression systems could give rise to functional differences in 5-HT4 receptor behavior.
- Published
- 2004
- Full Text
- View/download PDF
47. Agonist-like activity of antibodies directed against the second extracellular loop of the human cardiac serotonin 5-HT4(e) receptor in transfected COS-7 cells.
- Author
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Bozon V, Di Scala E, Eftekhari P, Hoebeke J, Lezoualc'h F, Fischmeister R, and Argibay J
- Subjects
- Adenylyl Cyclases metabolism, Animals, Antibody Specificity, Atrial Fibrillation etiology, Atrial Fibrillation immunology, Autoantibodies, COS Cells, Enzyme Activation, Epitopes chemistry, Epitopes genetics, Humans, In Vitro Techniques, Receptors, Serotonin genetics, Receptors, Serotonin metabolism, Receptors, Serotonin, 5-HT4, Recombinant Proteins chemistry, Recombinant Proteins genetics, Recombinant Proteins immunology, Recombinant Proteins metabolism, Transfection, Myocardium immunology, Myocardium metabolism, Receptors, Serotonin chemistry, Receptors, Serotonin immunology
- Abstract
We have previously reported that antipeptide antibodies directed against the second extracellular loop of the cardiac h5-HT4 receptor could block the activation of the L-type Ca channel in human atrial cardiomyocytes. In this paper we investigate the immunological and physiological activity of these antibodies, in a cell system expressing a larger amount of receptors than the atrial cells. The recombinant receptor was expressed at the surface of COS-7 cells under an active form (serotonin, EC50 = 1.81 x 10(-7) M), at a high level (375 +/- 25 fmol receptor/mg total protein) and was able to bind a specific ligand (GR113808) with a high affinity (Kd = 0.28 +/- 0.05 nM). In this system, the same anti-peptide antibodies used for the cardiac cells induced an "agonist-like" effect on the recombinant h5-HT4 receptor. These results are in line with those shown for others G-protein coupled receptors, as adrenoreceptors. In addition, this work showed that the effect of the antibodies is not only dependent on the epitopic region recognised but also on the molecular density and/or the cellular environment of the target receptors. Finally, our results support the hypothesis that the h5-HT4 receptor could be a new target for autoantibodies in patients with atrial arrhythmia.
- Published
- 2002
48. cGMP-mediated inhibition of cardiac L-type Ca(2+) current by a monoclonal antibody against the M(2) ACh receptor.
- Author
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Nascimento JH, Sallé L, Hoebeke J, Argibay J, and Peineau N
- Subjects
- 1-Methyl-3-isobutylxanthine pharmacology, 8-Bromo Cyclic Adenosine Monophosphate pharmacology, Adrenergic beta-Agonists pharmacology, Animals, Autoantibodies, Colforsin pharmacology, Enzyme Inhibitors pharmacology, Guanosine pharmacology, Guinea Pigs, Heart Ventricles cytology, In Vitro Techniques, Isoproterenol pharmacology, Membrane Potentials drug effects, Membrane Potentials physiology, Muscle Fibers, Skeletal metabolism, Myocardium cytology, Oxadiazoles pharmacology, Patch-Clamp Techniques, Phosphodiesterase Inhibitors pharmacology, Quinoxalines pharmacology, Receptor, Muscarinic M2, Antibodies, Monoclonal pharmacology, Calcium Channels, L-Type metabolism, Cyclic GMP pharmacology, Guanosine analogs & derivatives, Receptors, Muscarinic immunology, Receptors, Muscarinic metabolism
- Abstract
The effects of a monoclonal antibody (B8E5) directed against the second extracellular loop of the muscarinic M(2) receptor were studied on the L-type Ca(2+) currents (I(Ca,L)) of guinea pig ventricular myocytes using the whole cell patch-clamp technique. Similar to carbachol, B8E5 reduced the isoproterenol (ISO)-stimulated I(Ca,L) but did not significantly affect basal I(Ca,L). Atropine blocked the inhibitory effect of B8E5. The electrophysiological parameters of ISO-stimulated I(Ca,L) were not modified in presence of B8E5. Inhibition of I(Ca,L) by B8E5 was still observed when intracellular cAMP was either enhanced by forskolin or maintained constant by using a hydrolysis-resistant cAMP analog (8-bromoadenosine 3',5'-cyclic monophosphate) or by applying the phosphodiesterase inhibitor IBMX. The effect of B8E5 was mimicked by 8-bromoguanosine 3',5'-cyclic monophosphate, a potent stimulator of cGMP-dependent protein kinase, and prevented by a selective inhibitor of nitric oxide-sensitive guanylyl cyclase [1H-(1,2,4)oxadiazolo[4,3-a]quinoxaline-1-one]. These results indicate that the antibody B8E5 inhibits the beta-adrenergic-stimulated I(Ca,L) through activation of the M(2) muscarinic receptor and further suggest that the antibody acts not via the classical pathway of decreasing intracellular cAMP, but rather by increasing cGMP.
- Published
- 2001
- Full Text
- View/download PDF
49. Anti-SSA/Ro52 autoantibodies blocking the cardiac 5-HT4 serotoninergic receptor could explain neonatal lupus congenital heart block.
- Author
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Eftekhari P, Sallé L, Lezoualc'h F, Mialet J, Gastineau M, Briand JP, Isenberg DA, Fournié GJ, Argibay J, Fischmeister R, Muller S, and Hoebeke J
- Subjects
- Adult, Aged, Amino Acid Motifs, Amino Acid Sequence, Animals, Antibody Specificity, Autoimmune Diseases immunology, CHO Cells, Calcium Channels metabolism, Cricetinae, Cricetulus, Cross Reactions, Female, Heart Block congenital, Heart Block immunology, Humans, Immunity, Maternally-Acquired, Infant, Newborn, Ion Channel Gating, Ion Transport, Lupus Erythematosus, Systemic immunology, Male, Middle Aged, Molecular Sequence Data, Peptide Fragments chemistry, Peptide Fragments immunology, Pregnancy, Pregnancy Complications immunology, Rabbits, Receptors, Serotonin chemistry, Receptors, Serotonin genetics, Receptors, Serotonin, 5-HT4, Recombinant Fusion Proteins immunology, Transfection, Antibodies, Antinuclear immunology, Autoantigens immunology, Autoimmune Diseases complications, Heart Block etiology, Lupus Erythematosus, Systemic complications, Myocardium immunology, RNA, Small Cytoplasmic, Receptors, Serotonin immunology, Ribonucleoproteins immunology
- Abstract
The 52-kDa SSA/Ro (Ro52) ribonucleoprotein is an antigenic target strongly associated with the autoimmune response in mothers whose children develop neonatal lupus and congenital heart block. When sera from patients with systemic lupus erythematosus were used as autoimmune controls in an enzyme immunoassay to screen for antibodies against the human serotoninergic 5-HT4-receptor, a high correlation was found between the presence of anti-Ro52 protein antibodies in such sera and antibodies reacting with a synthetic peptide, corresponding to the second extracellular loop of the human 5-HT4 receptor (amino acid residues 165-185). Homology scanning between the 5-HT4 peptide and the sequence of the Ro52 protein indicated two potential common epitopes located between residues 365 and 396 of the Ro52 protein. Cross-reactivity was found between the peptide derived from the 5-HT4 receptor, and a peptide corresponding to residues 365-382 of the Ro52 protein. Autoantibodies, affinity-purified on the 5-HT4 receptor peptide, specifically recognized both the Ro52 protein and the 5-HT4 receptor protein in immunoblots. The affinity-purified antibodies antagonized the serotonin-induced L-type Ca channel activation on human atrial cells. This effect could explain the electrophysiological abnormalities in neonatal lupus.
- Published
- 2000
- Full Text
- View/download PDF
50. Calcium-dependent modulation of the plateau phase of action potential in isolated ventricular cells of rabbit heart.
- Author
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Papp Z, Peineau N, Szigeti G, Argibay J, and Kovács L
- Subjects
- Animals, Cadmium pharmacology, Caffeine pharmacology, Calcium Channels drug effects, Calcium Channels metabolism, Cells, Cultured, Female, Fura-2 metabolism, Heart Ventricles cytology, Heart Ventricles drug effects, Male, Patch-Clamp Techniques, Rabbits, Sarcoplasmic Reticulum drug effects, Sarcoplasmic Reticulum physiology, Sodium metabolism, Sodium-Calcium Exchanger drug effects, Sodium-Calcium Exchanger metabolism, Action Potentials physiology, Calcium metabolism, Myocardium cytology, Ventricular Function
- Abstract
[Ca2+]i-dependent modulation of the action potential has been studied in Fura-2 dialysed ventricular myocytes of the rabbit using the whole-cell current-clamp method. Fifteen consecutive action potentials (AP1-AP15) and [Ca2+]i transients were elicited at a frequency of 0.2 Hz. A single, brief application of caffeine (during AP9) first enhanced and thereafter attenuated the [Ca2+]i transients accompanying AP9 and AP10-AP12, respectively. This approach provided direct comparison between time courses of action potentials: during the initial steady state (e.g. AP8) and when Ca2+ release from the sarcoplasmic reticulum was increased by caffeine (AP9) or decreased by depletion (AP10). The increase in [Ca2+]i facilitated repolarization and decreased action potential duration. However, action potentials at reduced Ca2+ release (AP10) had longer duration than during steady state. The caffeine-induced changes in L-type Ca2+ current (ICa,L), during voltage-clamp conditions partially explained the effects of caffeine on action potentials. When ICa,L was blocked by 500 micromol L-1 Cd2+, enhanced [Ca2+]i transients revealed an extra current component which was outward at +10 mV and inward at the resting membrane potential (most probably the transient inward current). In the presence of Cd2+, however, AP8 and AP10 had identical time courses, suggesting that ICa,L alone was responsible for the lengthening of AP10. Alterations in the transmembrane Na+ gradient resulted in changes of the steady state action potential durations (AP8) consistently with the expected modulation of the Na+-Ca2+ exchange current. However, the contribution of this current to the [Ca2+]i-dependent behaviour of action potential plateau could not be demonstrated.
- Published
- 1999
- Full Text
- View/download PDF
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