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Background Our study aimed to evaluate changes in the contractile behavior of human myocardium after exposure to caffeine and taurine, the main active ingredients of energy drinks (EDs), and to evaluate whether taurine exhibits any inotropic effect at all in the dosages commonly used in EDs. Methods Myocardial tissue was removed from the right atrial appendages of patients undergoing cardiac surgery and prepared to obtain specimens measuring 4 mm in length. A total of 92 specimens were exposed to electrical impulses at a frequency of 75 bpm for at least 40 min to elicit their maximum contractile force before measuring the isometric contractile force (ICF) and duration of contraction (CD). Following this, each specimen was treated with either taurine (group 1, n = 29), or caffeine (group 2, n = 31) or both (group 3, n = 32). After exposure, ICF and CD measuring were repeated. Post-treatment values were compared with pre-treatments values and indicated as percentages. Results Exposure to taurine did not alter the contraction behavior of the specimens. Exposure to caffeine, in contrast, led to a significant increase in ICF (118 ± 03%, p

Methylene blue (MB) is a frequently used in patients with systemic inflammatory response syndrome with the effect of an increase in systemic vascular resistance. Recent studies assume that MB improves contractility and sensitizes myocardium to catecholamines.

Background Myxomatous degeneration of the mitral valve is a common pathological finding in mitral valve surgery and the most common reason for severe mitral valve regurgitation. Considering the importance of right ventricular remodeling and global function after mitral valve surgery we tried to elucidate a possible association of myxomatous mitral valve and impairment of right atrial and ventricular function, which might have an impact on global ventricular performance after mitral valve surgery. Methods Right atrial tissue was harvested from 47 patients undergoing mitral valve surgery. We took the trabeculae from the right auricle, which was resected at the right auricle for implementation of extracorporal circulation. The tissue was skinned and prepared in a 24 h-lasting procedure to create small fibers for hinging them in the "muscle machine", an experimental set-up, created for pCa-force measurements. Results Patients without myxomatous mitral valve developed significantly more force (4.0 mN ± 0.8 mN) at the highest step of calcium concentration compared to 2.7 mN ± 0.4 mN in group of patients with myxomatous valve degeneration (p 0.03). Calcium sensitivity in the myxomatous valve group was at pCa 6.0 and in the non-myxomatous group at pCa 5. Furthermore we observed a significant difference in ejection fraction (EF) among the groups: 49% in the non-myxomatous group versus 57% in the myxomatous group (p 0.03). In the non-myxomatous group 5 patients had diastolic dysfunction grade I-II (22,7%), in group I 10 patients (40%). This was also significant (p 0.04). Conclusions Patients with myxomatous mitral valve degeneration seem to have reduced force capacities. Calcium sensitivity is higher compared to the non-myxomatous group, which might be a compensatory mechanism to cover the physiological demand. Furthermore we suggest a higher incidence of diastolic dysfunction in patients with myxomatous mitral valve degeneration, which might have an impact on ventricular remodeling after mitral valve surgery.

Inosine, a break-down product of adenosine, has been recently shown to exert inodilatory and anti-inflammatory properties. We investigated the effects of inosine on ischemia/reperfusion injury in a rat heart transplantation model.Intraabdominal heterotopic transplantation was performed in Lewis rats. After 1h of ischemic preservation, reperfusion was started after application of either saline vehicle (control, n=12) or inosine (100 mg/kg, n=12). Coronary blood flow, left ventricular function, endothelium-dependent vasodilatation to acetylcholine and endothelium-independent vasodilatation to sodium nitroprusside, and high energy phosphate content were measured after 1 and 24h of reperfusion. In addition, the activation of the poly(ADP-ribose) polymerase was detected by immunhistology.After 1h, coronary blood flow (4.1+/-0.3 ml/(ming) vs 2.9+/-0.3 ml/(ming), p0.05), left ventricular systolic pressure (102+/-9 mmHg vs 83+/-4 mmHg, p0.05) and dP/dt (2765+/-609 mmHg/s vs 1740+/-116 mmHg/s, p0.05) were significantly higher in the inosine group in comparison to control. Vasodilatatory response to sodium nitroprusside was similar in both groups. Acetylcholine resulted in a significantly higher increase in coronary blood flow in the inosine group (76+/-5% vs 48+/-9%, p0.05). Energy charge potential was significantly higher in the inosine group (1.69+/-0.10 micromol/g vs 0.74+/-0.27 micromol/g, p0.05). After 24h, there was no difference between the groups in basal coronary blood flow, left ventricular systolic pressure, dP/dt, and the response to sodium nitroprusside. However, acetylcholine led to a still significantly higher response in the inosine group (112+/-13% vs 88+/-7%, p0.05). Immunhistologic stainings revealed activation of poly(ADP-ribose) polymerase in control animals which was abolished by inosine.Thus, inosine improves myocardial and endothelial function during early reperfusion after heart transplantation with a persisting beneficial effect against reperfusion induced graft coronary endothelial dysfunction. The effects of inosine are mediated at least partly by modulation of the peroxynitrite-poly(ADP-ribose) polymerase pathway.

Objective: Free radical production and related cytotoxicity during ischemia and reperfusion might lead to DNA strand breakage, which activates the nuclear enzyme poly-ADP-ribose synthetase and initiates an energy-consuming and inefficient cellular metabolic cycle with transfer of the adenosine diphosphate-ribosyl moiety of nicotinamide adenine dinucleotide (NAD+) to protein acceptors. We investigated the effects of poly-ADP-ribose synthetase inhibition on myocardial and endothelial function during reperfusion in an experimental model of cardiopulmonary bypass. Methods: Twelve anesthetized dogs underwent hypothermic cardiopulmonary bypass. After 60 minutes of hypothermic cardiac arrest, reperfusion was started after application of either saline vehicle (control, n = 6) or PJ34 (10 mg/kg), a potent poly-ADP-ribose synthetase inhibitor (n = 6). Biventricular hemodynamic variables were measured by means of a combined pressure-volume conductance catheter, and the slope of the end-systolic pressure-volume relationships was calculated at baseline and after 60 minutes of reperfusion. Left anterior descending coronary blood flow, endothelium-dependent vasodilatation to acetylcholine, and endothelium-independent vasodilatation to sodium nitroprusside were also determined. Results: The administration of PJ34 led to a significantly better recovery of left and right ventricular systolic function (P < .05) after 60 minutes of reperfusion. In addition, the inotropic adaptation potential of the right ventricle to an increased afterload was better preserved in the PJ34 group. Coronary blood flow was also significantly higher in the PJ34 group (P < .05). Although the vasodilatory response to sodium nitroprusside was similar in both groups, acetylcholine resulted in a significantly higher increase in coronary blood flow in the PJ34 group (P Conclusions: Poly-ADP-ribose synthetase inhibition improves the recovery of myocardial and endothelial function after cardiopulmonary bypass with hypothermic cardiac arrest.

Objective: Mucopolysaccharidosis is a group of inherited lysosomal storage disorders caused by the absence of an enzyme, contributing to the degradation of the Glycosaminoglycans (GAG). To evaluate if storage of GAGs affects the contractile capacity, we compared the contractile performance of patients with and without MPS in a skinned fiber model. Methods: Right auricle tissue from 12 patients (4 MPS, 8 Non-MPS) undergoing cardiac operation for Mitral Valve Stenosis (MS) or Mitral Valve Regurgitation (MR) was harvested prior to implementation of extracorporal Circulation (ECC). The trabeculae are resected from the right auricle; the tissue was dissected down to small bundles of fibers. They were chemically skinned by removal of cell membrane-dependent properties to gain the actin-myosinformation. These bundles are dissected in single fiber stripes. The fibers were exposed to a gradual increase of calcium concentration (pCa) and the corresponding force was measured and recorded. Results: 1.) pCa-force development was significant lower in fibers with MPS (p max 2.2 ± 0.1 mN) than in fibers with MS (3.4 ± 0.7 mN, p 0.03) or MR (4.6 ± 0.9 mN, p 0.04). 2.) The pCa-force values of fibers with mitral valve stenosis and regurgitation did not differ significantly at single steps of calcium concentration among each other (p 0.3). 3.) Fibers with MR developed significant more force at almost all steps of calcium concentration than those with MPS (p 0.02) 4.) Fibers with MS developed only once significant more force compared to MPS fibers: pCa 5.5: 1.6 mN vs. 0.3 mN, p 0.02. 5.) Calcium sensitivity is similar in patients with MPS and MR (pCa 4.5), but different in patients with MS (pCa 5). Conclusion: Patients with MPS develop significantly less force at similar calcium concentrations compared to patients with a mitral valve stenosis or regurgitation. We suggest that impairment of the contractile apparatus due to the accumulation of GAGs leads to early onset left ventricular hypertrophy and diastolic dysfunction limiting the ventricular filling. This stands in opposition to patients with mitral valve regurgitation with volume overload due to incomplete valve closure.

BACKGROUND This study was designed to investigate the effects of the selective endothelin-A receptor antagonist BQ123 on myocardial and endothelial function after reversible deep hypothermic ischemia and reperfusion. METHODS Isogenic intra-abdominal heterotopic heart transplantation was performed in Lewis rats. After one hour of cold ischemic preservation reperfusion was started after application of either saline vehicle or BQ123 (1 micromol/L). Left-ventricular pressure-volume relations and myocardial blood flow were assessed after one and 24 hours of reperfusion. Responses to endothelium-dependent vasodilator acetylcholine and endothelium-independent vasodilator sodium nitroprusside were also determined. RESULTS BQ123 significantly improved myocardial contractility, as indicated by the leftward shift of the systolic pressure-volume relation and significantly increased myocardial blood flow during early reperfusion (p < 0.05). Although myocardial function and baseline myocardial blood flow were similar in both groups after 24 hours of reperfusion, endothelium-dependent vasodilatation was still significantly higher in the BQ123 group (p < 0.05). CONCLUSIONS These results suggest that endothelin-A receptor antagonists may be useful in reducing ischemia/reperfusion injury after heart transplantation by preservation of myocardial and endothelial function.

Gender-based differences in the cardiac morphology and function in patients with volume-overload cardiac pathologies has been widely examined. However the relationship between gender and contractility is not well defined.

Body mass is reported to influence myocardial performance. Latest studies have emphasized the importance of negative inotropic Adipocyte-derived factors and assume an impact on cardiac contractile function. However the underlying mechanism remains unclear.

Recent studies suggested that the peroxynitrite-poly (ADP-ribose) polymerase (PARP) pathway is activated during acute allograft rejection. We investigated whether PARP inhibition improves transplant function during cardiac rejection. Isogeneic Lewis-to-Lewis and allogeneic Dark Agouti-to-Lewis rat cardiac transplants were studied under treatment with placebo or with the PARP-inhibitor INO-1001 (1 mk/kg/day), Functional, biochemical and histological analysis were performed 3 and 5 days after transplantation. After 3 days, baseline left ventricular pressure-volume relationships did not differ between the groups. However, coronary blood flow (4.3 +/- 0.5 vs. 2.2 +/- 0.2 vs. 4.1 +/- 0.3 ml/min/g, P < 0.05) and contractile response to dobutamine (Delta+dP/dt: 98 +/- 11 vs. 57 +/- 7 vs. 88 +/- 8%, P < 0.05) decreased significantly in the placebo group, which was abolished by INO-1001. Vasodilatory response to acethylcholine was reduced in the placebo group (78 +/- 6 vs. 36 +/- 9 vs. 72 +/- 7%, P < 0.05). After 5 days, baseline systolic and diastolic pressure-volume relationships were impaired (P < 0.05) in the placebo group and the response to dobutamine and to acethylcholine deteriorated further which was abolished by INO-1001. Histology confirmed mild to moderate rejection after 3 days and severe acute rejection after 5 days in the allogeneic groups. Thus, contractile and vasomotor dysfunction occur in a typical time dependent manner during cardiac rejection, which can be reduced by PARP-inhibition.

BACKGROUND This study investigated the changes of catecholamine responsiveness and beta-adrenergic receptor/adenylyl cyclase pathway during acute cardiac transplant rejection. METHODS Isogeneic Lewis to Lewis and allogeneic Dark Agouti (DA) to Lewis rat cardiac transplants were studied 3 and 5 days after heterotopic intraabdominal transplantation (n=6/group). Myocardial blood flow (MBF), left ventricular systolic pressure (LVSP), maximum pressure development (+dP/dt), and end-diastolic pressure (LVEDP) were measured using an intraventricular balloon. Contractile response to dobutamine (5 microg/kg/min) was also assessed. In separate groups beta-adrenergic receptor density and adenylyl cyclase activity were measured in the grafts, in the recipients' native hearts and in native hearts of sham-operated controls. RESULTS During mild to moderate rejection cardiac function indices remained unchanged, although MBF and contractile response to dobutamine decreased significantly (P

The aim of the study was to characterize the course of systolic and diastolic function, myocardial blood flow, and histologic changes during acute rejection in a model of heterotopic transplantation in rats. For this purpose isogenic Lewis-to-Lewis and allogenic DA (Dark Agouti)-to-Lewis rat cardiac transplants were studied 1 hour and 1, 3, and 5 days, respectively, after heterotopic intraabdominal transplantation. Myocardial tissue blood flow (MBF) was assessed by the hydrogen-clearance method. An implanted balloon was used to measure pressure–volume relations in the transplanted heart. Myocardial water content was determined at the end of the experiments, and histologic examinations were performed. The MBF recovered during the first day postoperatively in both groups and decreased again in the allogenic group after 3 and 5 days (p < 0.05); it remained stable in the isogenic group. Myocardial relaxation was already prolonged in the allogenic group after 3 days and deteriorated further. Left ventricular end-diastolic pressure progressively increased in the allogenic group, whereas it remained unchanged in the isogenic group up to 5 days. After recovery from ischemia, the left ventricular peak systolic pressure was stable in the isogenic group for the entire further observation period, but it significantly decreased in the allogenic group after 5 days (p < 0.05). Myocardial water content showed a significant increase in the allogenic group compared to that in the isogenic group after 5 days. In the allogenic group histologic examination confirmed mild to moderate rejection after 3 days and severe acute rejection after 5 days. Thus, after recovery from ischemia, mild to moderate cardiac rejection was associated with reduced MBF and impaired relaxation. In a typical sequence, generation of edema and impaired diastolic compliance were terminally followed by systolic dysfunction during severe rejection.

Objective: Previous studies suggested that endothelin-1 (ET-1) may play a pathophysiological role in myocardial ischemia/reperfusion injury. This study was designed to investigate the effects of the selective ET-A receptor antagonist BQ123 and the selective ET-B receptor antagonist BQ788 on myocardial and endothelial function after reversible deep hypothermic ischemia in a heterotopic rat heart transplantation model. Methods: Isogenic intraabdominal heterotopic transplantation was performed in Lewis rats. After 1 h of cold ischemic preservation reperfusion was started either after application of placebo (control), BQ123 (3 μmol/kg/min), BQ788 (3 μmol/kg/min), ET-1 (8 pmol/kg/min) or simultaneous infusion of BQ123 or BQ788 and ET-1, respectively ( n =12 each). An implanted balloon was used to obtain pressure–volume relations of the transplanted heart. Myocardial blood flow (MBF) was assessed by the hydrogen-clearance method. Measurements were taken after 1 and 24 h of reperfusion. Endothelium-dependent vasodilation to acetylcholine (ACH) and endothelium-independent vasodilation to sodium nitroprusside were also determined. Results: Both BQ123 and BQ788 significantly improved myocardial and endothelial functional recovery during early reperfusion, whereas ET-1 significantly impaired myocardial and endothelial function. Simultaneous infusion of ET-1 diminished the effects of BQ123 and BQ788. Although myocardial function and baseline MBF were similar in all groups after 24 h of reperfusion, endothelium dependent vasodilation to ACH was still significantly higher in the BQ123 and BQ788 groups and lower in the ET-1 groups ( p

Global myocardial ischemia and reperfusion injury play a major role in early postoperative myocardial graft dysfunction. The aim of the present study was to investigate the effects of the nitric oxide (NO) precursor L-arginine on myocardial and endothelial function after hypothermic ischemia and reperfusion in a heterotopic rat heart transplantation model. After 1 hour ischemic preservation, reperfusion was started after application of placebo (control, n = 12) or L-arginine (L-Arg 40 mg/kg, n = 12), a substrate of NO synthesis. Myocardial blood flow (MBF) was assessed by the hydrogen clearance method. An implanted balloon was used to obtain pressure-volume relations of the transplanted heart. Left ventricular developed pressure (LVDP), rate of pressure development (dP/dt), end-diastolic pressure (LVEDP), isovolumic relaxation constant (TE), and MBF were measured after 60 minutes and 24 hours of reperfusion. endothelium-dependent vasodilatation in response to acetylcholine (ACh) and endothelium-independent vasodilatation in response to sodium nitroprusside (SNP) were also determined. After 1 hour the MBF was significantly higher in the L-Arg group (3.6 +/- 0.6 vs. 1.9 +/- 0.2 ml/min/g, p < 0.05). The L-Arg group showed better recovery of systolic function and myocardial relaxation (LVDP 106 +/- 6 VS. 70 +/- 7 mmHg, p < 0.05; maximal dP/dt 5145 +/- 498 vs. 3410 +/- 257 mmHg/s, P < 0.05; TE 12.1 +/- 0.9 vs. 16.1 +/- 1.5 ms, p < 0.05, at an intraventricular volume of 80 microliters). LVEDP was similar in the two groups. After 24 hours no difference was found between the groups for basal MBF, LVP dP/dt, TE, LVEDP, or the response of MBF to SNP. However, ACh led to a significantly higher increase in MBF in the L-Arg group (52 +/- 8% vs. 29 +/- 7%, p < 0.05). These results indicate that (1) NO donation improves myocardial and endothelial functional recovery during early reperfusion after heart transplantation; and (2) initial treatment with L-Arg has a persisting beneficial effect against reperfusion-induced graft coronary endothelial dysfunction during late reperfusion.