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The mechanism of imidazole-induced contraction on the bovine tracheal smooth muscle was investigated. Imidazole induced muscle contraction in a concentration-dependent manner on bovine, porcine and guinea-pig tracheas, but not in rat or mouse. In bovine tracheas, imidazole was cumulatively applied and induced muscle tension and increasesd intracellular Ca2+ level in a concentration -dependent manner. Imidazole, even at 300 µM, the concentration at which maximum contractile response occurs, did not significantly increase in cAMP content relative to control. Atropine inhibited imidazole-induced contraction at a concentration- dependent manner and pretreatment of hemicholinium-3 almost abolished imidazole-induced contraction. Conversely, pretreatment of tripelennamine, indomethacin or tetrodotoxin did not affect imidazole-induced contraction. Acetylcholine or eserine induced contraction in bovine, porcine, guinea pig, rat and mice trachea in a concentration-dependent manner. However, there was little difference in the rank order of maximum contraction of these agents. Imidazole-induced contraction was greater in bovine trachea compared to the other species tested. Further, cAMP did not appear to play a role in imidazole-induced contraction, suggesting other mechanisms, such as the release of endogenous acetylcholine.

Recent studies have shown that phloridzin, an inhibitor of sodium-glucose cotransporter (SGLT), strongly decreases high K+-induced contraction in phasic muscle, such as tenia coli, but slightly affects tonic muscle, such as trachea . In this study, we examined the inhibitory mechanism of phloridzin on high K+-induced muscle contraction in rat ileum, a phasic muscle. Phloridzin inhibited the high K+-induced contraction in the ileum and the aorta, and the relaxing effect of phloridzin at 1 mM in the ileum was approximately five-fold more potent than that in the aorta. The expression of SGLT1 mRNA in the ileum was higher than that of the aorta. Phloridzin significantly inhibited NADH/NAD ratio and phosphocreatine (PCr) content in the ileum; however, application of pyruvate recovered the inhibition of contraction and PCr content, but had no effect on ratio of NADH/NAD. High K+ increased 2-(N (7-nitrobenz-2-oxa-1,3-diazol-4-yl) amino)-2-deoxyglucose (2-NBDG) uptake in ileal smooth muscle cells, and phloridzin inhibited the increase in a concentration-dependent manner. These results suggest that phloridzin inhibits high K+-induced contraction because of the inhibition of energy metabolism via the inhibition of SGLT1.

Eyes are supplied O2 through the cornea and vessels of the retina and iris, which are tissues characterized by aerobic metabolism. Meanwhile, there are no reports on the association between iris sphincter contraction and aerobic metabolism. In this paper, we studied the aforementioned association. Eyes from adult pigs of either sex were obtained from a local abattoir. A muscle strip was connected to a transducer to isometrically record the tension. O2 consumption was measured using a Clark-type polarograph connected to a biological oxygen monitor. Creatine phosphate (PCr) and adenosine triphosphate (ATP) contents were measured in the muscle strips by high-performance liquid chromatography (HPLC). Iris sphincter muscles were measured in resting, contractile or hypoxic phases. Contraction was induced by hyperosmotic 65 mM KCl (H-65K+) or carbachol (CCh), and hypoxia was induced by aeration with N2 instead of O2 or by addition of sodium cyanide (NaCN). H-65K+- and CCh-induced muscle contraction, involved increasing O2 consumption. Hypoxia and NaCN significantly decreased H-65K+- and CCh-induced muscle contraction and/or O2 consumption and PCr contents. Our results suggest that the contractile behavior in porcine iris sphincter highly depends on mitogen oxidative metabolism.

The effects of various selective phosphodiesterase (PDE) inhibitors on carbachol (CCh)-induced contraction in the bovine abomasum were investigated. Various selective PDE inhibitors, vinpocetine (type 1), erythro-9-(2-hydroxy-3-nonyl) adenine (EHNA, type 2), milrinone (type 3), Ro20-1724 (type 4), vardenafil (type 5), BRL-50481 (type 7) and BAY73-6691 (type 9), inhibited CCh-induced contractions in a concentration-dependent manner. Among the PDE inhibitors, Ro20-1724 and vardenafil induced more relaxation than the other inhibitors based on the data for the IC50 or maximum relaxation. In smooth muscle of the bovine abomasum, we showed the expression of PDE4B, 4C, 4D and 5 by RT-PCR analysis. In the presence of CCh, Ro20-1724 increased the cAMP content, but not the cGMP content. By contrast, vardenafil increased the cGMP content, but not the cAMP content. These results suggest that Ro20-1724-induced relaxation was correlated with cAMP and that vardenafil-induced relaxation was correlated with cGMP in the bovine abomasum. In conclusion, PDE4 and PDE5 are the enzymes involved in regulation of the relaxation associated with cAMP and cGMP, respectively, in the bovine abomasum.

The effects of papaverine on carbachol (CCh) -and high K+- induced contraction in the bovine abomasum were investigated. Papaverine inhibited CCh (1 µM) -and KCl (65 mM) -induced contractions in a concentration-dependent manner. Forskolin or sodium nitroprusside inhibited CCh-induced contractions in a concentration-dependent manner in association with increases in the cAMP or cGMP contents, whereas papaverine increased cGMP contents only at 30 µM. Changes in the extracellular Ca2+ from 1.5 mM to 7.5 mM reduced verapamil-induced relaxation in high K+-depolarized muscles, but papaverine-induced relaxation did not change. Futhermore, papaverine (30 µM) and NaCN (300 µM) decreased the creatine phosphate contents. These results suggest that the relaxing effects of papaverine on the bovine abomasum are mainly due to the inhibition of aerobic energy metabolism.

A high-K(+), Na(+)-deficient (isosmotic 154 mM K(+) and 0 mM Na(+); I-154 K(+)) solution induced contraction followed by gradual relaxation of the smooth muscles of the porcine trachea, while hyperosmotic addition of 65 mM KCl (H-65 K(+)) induced a large sustained contraction. The I-154 K(+) solution also induced a sustained increase in [Ca(2+)](i) level. Decreases in muscle tension and increases in cellular water content were both prevented by the addition of sucrose or NaCl in the porcine trachea. An additional application of phloridzin inhibited recoveries of I-154 K(+) solution by addition of NaCl in the porcine trachea. Addition of pyruvate or oxaloacetate recovered the I-154 K(+) solution-induced relaxation in the porcine trachea. Although application of I-154 K(+) solution did not affect PCr and ATP contents in the bovine trachea, the solution induced a gradual decrease of PCr content in the porcine trachea. Moreover, application of pyruvate or oxaloacetate recovered the I-154 K(+) solution-induced decreases of PCr content in the porcine trachea. Phloridzin inhibited H-65 K(+)-induced contraction in porcine, but not in bovine trachea. In conclusion, the I-154 K(+) solution-induced relaxation in the porcine trachea is probably due to swelling of cells and inhibition of glucose utilization. Moreover, the inhibition of glucose utilization in I-154 K(+) medium in porcine trachea is different from that of bovine trachea.

The effects of various selective phosphodiesterase (PDE) inhibitors on muscle contractility and cyclic nucleotide contents in the guinea pig gall bladder were investigated. Various selective PDE inhibitors, vinpocetine (type 1), erythro-9-(2-hydroxy-3-nonyl)adenine (EHNA, type 2), milrinone (type 3), Ro20-1724 (type 4), and zaprinast (type 5), inhibited CCh-induced contractions in a concentration-dependent manner. The rank order of potency for the gall bladder was Ro20-1724vinpocetineEHNAmilrinonezaprinast, which was different from that of the trachea, taenia coli, and aorta. In the presence of CCh (0.3 muM), vinpocetine, milrinone, and Ro20-1724 each increased cAMP content, but not cGMP. By contrast, zaprinast increased cGMP content, but not cAMP, and EHNA increased both cAMP and cGMP contents. These results suggest that vinpocetine-, milrinone-, and Ro20-1724-induced relaxation was correlated with cAMP, zaprinast-induced relaxation was correlated with cGMP, and that EHNA-induced relaxation was correlated with cAMP and cGMP in the guinea pig gall bladder. In conclusion, the effect of PDE inhibitors in the guinea pig gall bladder was different from those in smooth muscles, such as the trachea, taenia coli, and aorta.

Effects of various selective phosphodiesterase (PDE) inhibitors on muscle contractility and cyclic nucleotide contents in guinea pig taenia coli were investigated. Forskolin and sodium nitroprusside inhibited carbachol (CCh)-induced contraction in a concentration-dependent manner. Various selective PDE inhibitors, vinpocetine (type 1), erythro -9-(2-hydroxy-3-nonyl)adenine (EHNA, type 2), milrinone (type 3), Ro20-1724(type 4) and zaprinast (type 5) inhibited CCh-induced contraction in a concentration-dependent manner, but the inhibition of milrinone was noticeably smaller than that of the other PDE inhibitors. The rank order of potency was zaprinast > vinpocetine > EHNA > Ro20-1724 > milrinone. In the presence of CCh (0.3 microM), vinpocetine and Ro20-1724 both increased cAMP content, but not cGMP. By contrast, EHNA and zaprinast both increased cGMP content, but not cAMP. Pretreatment with ODQ (30 microM), a soluble guanylyl cyclase inhibitor, decreased the inhibition of CCh-induced contraction by EHNA or zaprinast. Pretreatment with SQ22536 (100 microM), an adenylyl cyclase inhibitor, decreased the inhibition of CCh-induced contraction by vinpocetine or Ro20-1724. In conclusion, it was indicated that vinpocetine- or Ro20-1724-induced relaxation was correlated with cAMP but EHNA- or zaprinast- induced relaxation was correlated with cGMP.

Gymnema sylvestre (GS) is one of the Asclepiad strains that grows in South-east Asia. Their therapeutic effects for treating diabetes mellitus, rheumatic arthritis and gout have been well known for a long time. However, the problem is that GS suppresses sweetness and tastes bitter. For this study, we chose Gymnema inodorum (GI) instead of GS, since it has an advantage that it does not suppress sweetness nor is it bitter in taste. In this paper, effects of glucose availability of some saponin fractions (F-I to F-IV) extracted from GI leaves, which were obtained by high-performance liquid chromatography were studied on a high K(+)-induced contraction of guinea-pig intestinal smooth muscle, O2 consumption on guinea-pig ileum, glucose-evoked transmural potential difference (delta PD) of guinea-pig everted intestine and blood glucose level in glucose tolerance tests on rats. The extracts of GI leaves suppressed the intestinal smooth muscle contraction, decreased the O2 consumption, inhibited the glucose evoked-transmural potential, and prevented the blood glucose level. Our studies suggest that the component of GI inhibits the increase in the blood glucose level by interfering with the intestinal glucose absorption process.

The effect of CV-3988, a platelet activating factor antagonist, in the treatment of endotoxic shock was evaluated from the changes in plasma 6-keto-PGF1 alpha and thromboxane B2 concentrations. The animals consisted of 10 beagle dogs anesthetized with pentobarbital sodium and divided into a treatment group (n = 5) and a control group (n = 5). Endotoxic shock was experimentally induced in both groups by intravenous administration of endotoxin (lipopolysaccharide, 3 mg/kg). The treatment group was intravenously given 10 mg/kg of CV-3988 for 10 min from immediately after endotoxin. Mean aortic pressure, cardiac output and urine volume were remarkably decreased after the administration of endotoxin to both groups. These parameters were higher after the administration of CV-3988, in the treatment group than in the control group. Furthermore, the increase in plasma 6-keto-PGF1 alpha and thromboxane B2 concentrations was significantly inhibited. These results suggest the effectiveness of CV-3988 in the treatment of endotoxic shock.

The therapeutic effect of ulinastatin (25,000 U/kg, i.v.) on endotoxin-induced shock was compared with that of methylprednisolone (30 mg/kg, i.v.) in 17 anesthetized dogs. Both of these drugs had almost the same tendency to improve the hemodynamics, arachidonate cascade metabolites and pulmonary surface activity. There was little difference between the effectiveness of ulinastatin and that of methylprednisolone. It was newly confirmed that the release of 6-keto-PGF1 alpha, thromboxane B2 and leukotriene B4, arachidonate cascade metabolites and chemical mediators associated with endotoxin-induced shock, were significantly (p < 0.01 and p < 0.05) decreased by ulinastatin in the same way as methylprednisolone. These results suggest that ulinastatin is as useful as methylprednisolone for the treatment of endotoxin-induced shock.

A shock model was experimentally produced by intravenous injection of a lethal dose (3 mg/kg) of endotoxin under general anesthesia induced by pentobarbital sodium using 7 beagles. The effect of this endotoxic shock on the reticuloendothelial function was investigated. The blood endotoxin concentration peaked immediately after administration and decreased subsequently. However, the value still remained on an increased level (1,051 pg/ml) even at 360 min after endotoxin treatment. The lipid emulsion test as an index of reticuloendothelial phagocytotic activity and the arterial ketone body ratio as an index of the energy charge in the liver decreased after endotoxin treatment and failed to recover during the experiment. Fibronectin, one of opsonic proteins, tended to decrease after injection of the endotoxin and was significantly (p < 0.01) low at 180 and 360 min compared with the value before injection of the endotoxin. These results suggested the depression of the reticuloendothelial function during endotoxin-induced shock.

Accuracy assessment was undertaken under varying hemodynamic conditions for a lung water volume measurement device which is based on the principle of a double indicator dilution method using heat and sodium ions. Changes in extravascular thermal volume were investigated in dogs with endotoxin-induced shock. The isoproterenol- or propranolol-induced changes in hemodynamics had no effect on the measurement. This confirmed the high accuracy of this measuring method. The measurement revealed a tendency for the extravascular thermal volume to gradually increase (p < 0.05) during endotoxin shock. This confirmed the gradual progression of pulmonary edema during endotoxin shock.

Ouabain was examined for effect on the mechanical response of the ileum isolated from eleven animal species, dog, cat, rabbit, guinea pig, rat, vole, mouse, cock, pigeon, frog and toad. In isotonic recording, ouabain induced a sustained contraction in ileum isolated from some species. It caused a transient contraction on following by a relaxation in others. The ouabain sensitivities of a contractile response in the ilea from eleven species, as demonstrated by the estimation of ED50, was divided into four groups. That is, a high sensitive group; frog (ED50=9.0×10-8M), cat (9.3×10-8M), pigeon (3.5×10-7M) and cock (5.1×10-7M), a sensitive group; rabbit (1.1×10-6M), vole (2.3×10-6M) and guinea pig (2.7×10-6M), a low sensitive group; mouse (1.7×10-5M) and rat (9.7×10-5M) and an insensitive group; toad (>10-3M). Although ED50 in the dog was not able to be calculated, its sensitivity seems to belong to the high sensitive group. On the other hand, ED50 of acetylcholine (Ach) in thc ilea, isolated from these species were estimated in a narrow range of concentration from 5×10-9M to 5×10-8M. There were species differences in ouabain sensitivity for ileal contractile response but not in Ach sensitivity. A distinct correlation was found between the mechanical response to ouabain and the inhibitory potency of ouabain for Na, K-ATPase reported by Repke et al. These results seem to confirm that ouabain may induce a contraction by a mechanism which inhibits an electrogenic Na pump or Na, K-ATPase in the intestinal smooth muscle cell and which induces a depolarization.

Subcellular distribution of &lt109&gtCd and &lt109&gtCd incorporation into cadmium-binding protein (Cd-BP) were investigated in respective tissues of Cd-pretreated and intact control male rats and Japanese quail injected intravenously &lt109&gtCd-cadmium chloride. The liver contained the highest level of &lt109&gtCd of all the organs in the animals and birds examined. The largest amount of &lt109&gtCd was determined in the soluble cytoplasmic fraction derived from the homogenates of the liver, kidney and pancreas of control rats, as well as from those of the liver, kidney, pancreas and proventriculus of control quail. The crude nuclear fraction of the gastric gland of the control rats took up nearly half the amount of &lt109&gtCd contained in the homogenate of this gland of the control rats. Cd-exposure had in no case any significant effect either on the &lt109&gtCd uptake by the whole tissue or on the compartmentalization of &lt109&gtCd in the soluble fraction of any tissues in the rats and quail. In rats, as well as in quail the Sephadex gel filtration of the soluble fraction of each tissue gave rise to two peaks of &lt109&gtCd in the elution profile. The first peak was a minor one shown at the exclusion limit of Sephadex G-75 and the second peak a major one having an elution factor of approximately 2.0. The second peak of &lt109&gtCd was associated with a slight absorbance of ultraviolet (260nm) in the liver, but not in any other organ, of control rats and quail. Cd-exposure intensified both &lt109&gtCd peak and absorbance of ultraviolet. The second component of &lt109&gtCd was considered to be Cd-BP from its elution profile on Sephadex G-75. The Cd-BP-like component may be synthesized not only in the liver and kidney but also in the pancreas and gastric gland, regardless of the species of animal. Some possible mechanisms were discussed when Cd-BP had failed to prevent the initiation of Cd-toxicity.

Effect of removal of the external Potassium ion (K removal) was examined on the mechanical response of the ileum isolated from thirteen animal species; monkey, dog, cat, rabbit, guinea pig, rat, mouse, volt, deer, cock, pigeon, frog and toad. In isotonic recording, K removal induced a sustained contraction in ileum isolated from cat and deer, however, a transient contraction followed by a relaxation in the ileum isolated from other species. Readmission of potassium to the K-free solution produced a quick relaxation in the muscles of pigeon, frog, guinea pig, rat and mouse. Ouabain (1×10-5 M) inhibited the relaxation induced by the readmission of K. There were species differences in contractile activity to K removal; the relative height of ileal contraction induced by K removal was in the order of pigeon, frog, vole, dog, cat, deer, monkey, cock, guinea pig, rat, rabbit, mouse and toad, respectively. Furthermore, the magnitude of the contractile responses to K removal in the ilea isolated from the various kinds of animals correlated with the ED50 of ouabain for a contractile response in the ilea from these animals, as reported by Shimizu et al. (1979). These results probably confirm the concept that K removal and ouabain induce a contraction which is due to the inhibition on an electrogenic Na pump in muscle cells of the ileum.

A transport mechanism of methylmercury to egg albumen was investigated in laying Japanese quail which had received a single intravenous injection of 203Hg-methylmercuric chloride. Whole body distribution of 203Hg was analyzed by means of autoradiography. It was notable that the uptake of 203Hg was higher in the oviduct than in any other tissue checked. Further, the 203Hg was detectable in egg albumen which had been synthesized and secreted in the magnumean portion of the oviduct. From the observations mentioned above, it is suggested that methylmercury in the vascular system was taken up cumulatively by the oviduct and deposited in egg albumen by the secretory way. On the tissue level of the benzene-extractable form of 203Hg compounds (RHg) quantitative analysis was made in the respective organs. RHg decreased from the blood and liver with the lapse of time. The renal level of RHg showed a gradual increase which was followed by a rapid decrease. In contrast to the tissue tested above, a magnumean uptake of RHg increased gradually and reached the highest level of the four tissue after 24 hours. The RHg content was analyzed in the egg shell, albumen and yolk. It was the largest in the albumen and second largest in the yolk, but negligible in the shell. In 7 eggs laid over a period of 8 days after the injection, the total RHg content was approximately 44% of the dose of the radiocompound administered. The largest amount of RHg was found in the albumen of an egg the third in the order of oviposition after the injection. The fecal and urinary content of 203Hg was approximately 23% of the dose during the same period of time. These quantitative data suggest that the major part of methylmercury in the body is transported into egg albumen via the secretory mechanism of the magnumean portion of the oviduct. Starch gel electrophoresis of the soluble cytoplasmic fraction of the magnumean homogenate and of egg albumen revealed that 203Hg was associated with protein bands which had migrated near the front. The protein bands were considered to be ovalbumin. It was confirmed from an examination in vitro that 203Hg-methylmercuric chloride bound to a purified hen's ovalbumin preparation. These results mentioned above suggest that methylmercury is readily bound to ovalbumin which was newly synthesized in large quantity in the magnumean portion of the oviduct.