Effect of thienorphine on intestinal transit and isolated guinea-pig ileum contraction

AIM: To evaluate the effect of thienorphine on small intestinal transit in vivo and on guinea-pig ileum (GPI) contraction in vitro . METHODS: The effects of thienorphine on intestinal transit were examined in mice and in isolated GPI. Buprenorphine and morphine served as controls. The distance traveled by the head of the charchol and the total length of the intestine were measured in vivo . Gastrointestinal transit was expressed as a percentage of the distance traveled by the head of the marker relative to the total length of the small intestine. The isolated GPI preparations were connected to an isotonic force transducer and equilibrated for at least 1 h before exposure to drugs. Acetylcholine was used for muscle stimulation. RESULTS: Thienorphine (0.005-1.0 mg/kg, ig ) or bu-prenorphine (0.005-1.0 mg/kg, sc ) dose-dependently significantly inhibited gut transit compared with saline. Thienorphine inhibited gut transit less than buprenorphine. The maximum inhibition by thienorphine on the intestinal transit was 50%-60%, whereas the maximum inhibition by morphine on gut transit was about 100%. Thienorphine also exhibited less inhibition on acetylcholine-induced contraction of GPI, with a maximum inhibition of 65%, compared with 93% inhibition by buprenorphine and 100% inhibition by morphine. Thienorphine induced a concentration-dependent decrease in the basal tonus of spontaneous movement of the GPI, the effect of which was weaker than that with buprenorphine. The duration of the effect of thienorphine on the GPI was longer than that with buprenorphine. CONCLUSION: Thienorphine had less influence, but a longer duration of action on GPI contraction and moderately inhibited intestinal transit.

Relaxation effects of matrine on guinea-pig aortic smooth muscles

Objective The present in vivo study was undertaken to determine whether matrine,a kind of traditional Chinese medicinal alkaloid,would relax the isolated guinea pig aortic smooth muscles,if so,to investigate the mechanism involved.Methods The concentration-dependent relaxation response to matrine was studied in phenylephrine or potassium chloride precontracted guinea pig aortic rings.Results Matrine(1×10-4 M-3.3×10-3 M)relaxed the endothelium denuded aortic rings precontracted submaximally with phenylephrine,in a concentration-dependent manner,and it's preincubation(3.3×10-3 M)produced a significant rightward shift in the phenylephrine dose-response curve,but had no effects on the potassium chloride-induced contraction.The anticontractile effect of matrine was not reduced by the highly selective ATP-dependent K+ channel blocker glibenclamide(10-5 M),the non-selective K+ channel blocker tetraethylammonium(10-3 M),as well as the β-antagonist propranolol(10-5 M).In either "normal" or "Ca2+-free" bathing medium,the phenylephrine-induced contraction was attenuated by matrine(3.3×10-3 M),indicating the vasorelaxation was due to inhibit of intracellular and extracellular Ca2+ mobilization.Conclusions The results obtained clearly demonstrated that matrine inhibits phenylephrine-induced contractions by inhibiting activation of α-adrenoceptor and interfering with both the release of intracellular Ca2+ and the influx of extracellular Ca2+.

The Distribution of the 5-hydroxytryptamin(5-HT) Immunoreactive Cells in the Pancreas of Guinea-pig

Immunocytochemical localization of 5-hydroxytryptamine (5-HT) containing cells of the guinea-pig pancreas was studied by means of PAP-glucose oxidase-DAB-nickel (PAP-GDN) and PAPstaining methods on paraffin sections. In this study we demonstrated the presence of 5-HTimmunoreactive cells in the endocrine (islets) and exocrine pancreas of the guinea-ping. Cells exhib-iting 54-HT immunoreactivity were found in the center and the periphery of the pancreatic islets. The5-HT immunoreactive granules were evenly distributed throughout the cytoplasm, but was faint inthe nuclei. Cells of this type were also distributed in the exocrine pancreas. Grouped or single or single cellsoccurred intercalatedly between acinar cells, as well as in the epithlium of ducts and in the connectivetissues near the ducts or acini.

Relaxant Effects of Matrine on Aortic Smooth Muscles of Guinea Pigs

Objective To determine whether matrine, a kind of traditional Chinese medicinal alkaloid, can relax the aortic smooth muscles isolated from guinea pigs and to investigate the mechanism of its relaxant effects. Methods Phenylephrine or potassium chloride concentration-dependent relaxation response of aortic smooth muscles to matrine was studied in the precontracted guinea pigs. Results Matrine （1×10^-4 mol/L -3.3×10^-3 mol/L） relaxed the endothelium-denuded aortic rings pre-contracted sub-maximally with phenylephrine, in a concentration-dependent manner, and its pre-incubation （3.3× 10^- 3 mol/L） produced a significant rightward shift in the phenylephrine dose-response curve, but had no effects on the potassium chloride-induced contraction. The anti-contractile effect of matrine was not reduced by the highly selective ATP-dependent K^＋ channel blocker glibenclamide （10.5 mol/L）, either by the non-selective K^＋channel blocker tetraethylammonium （10^-3 mol/L）, or by the β-antagonist propranolol （10^-5 mol/L）. In either ＂normal＂ or ＂Ca^2＋-free＂ bathing medium, the phenylephrine-induced contraction was attenuated by matrine （3.3×10^-3 mol/L）, indicating that the vasorelaxation was due to inhibition of intracellular and extracellular Ca^2＋ mobilization. Conclusion Matrine inhibits phenylephrine-induced contractions by inhibiting activation of α-adrenoceptor and interfering with the release of intracellular Ca^2＋ and the influx of extracellular Ca^2＋.

补肾活血等中药对豚鼠庆大霉素耳毒性的预防作用

本研究以耳廓反射，耳锅生物电及耳锅铺片毛细胞形态学改变为指标，用活血化瘀，通经活络，补肾纳气等中药组成的方剂，观察对豚鼠庆大霉素耳毒性的防治作用。结果表明本方剂能明显减轻庆大霉素的耳毒性作用。

Studies on the Role of Sodium／Hydrogen Exchange System in Myocardial Ischemia－Reperfusion Injury

This study aimed at the exploration of the relationship between Na+-H+ exchange system and myocardial ischemia-reperfusion injury(MRI)in an attempt to provide a theoretic basis for the prevention and treatment of MRI.We used the isolated working guinea pig hearts as the experimental model to mimick cardiopulmonary bypass,which included 120 min hypothermic ischemic cardioplegic arrest followed by 60 min normothermic reperfusion.The hearts were divided into 2 groups:the control group receiving St.Thomas'Hospital Solution(STS)and the treated group receiving STS+ amiloride,a Na+-H+ exchangeblocker.The results showed that during reperfusion,[Na+]i and [Ca2+]i overloads,poor recovery of cardiac function,increases in CPK release and OFR generation,reduction of ATP content and serious damage of ultrastructure were seen in group 1;whereas there were no [Na+]i and [Ca2+]i overloads and better recovery of cardiac function accompanied by improved results of biochemical assay and less damage of ultrastructure was found in group 2.Our study indicates that amiloride can inhibit Na+-H+ exchange system in cardiac cells during early reperfusion period,which prevents [Na+]i overload produced by Na+-H+ exchange,and stops Na+-Ca2+ exchange activated by high level of [Na+]i,thus attenuating [Ca2+]ioverload caused by Na+-Ca2+ exchange and myocardial injury.Therefore,we conclude that Na+-H+ exchange blocker,amiloride,can exert significant protective effects on MRI and its use may prove to be a new clinical approach to prevention and cure of MRI.

CLOFILIUM, A POTENT BLOCKER OF SODIUM AND CALCIUM CHANNELS IN GUINEA-PIG VENTRICULAR MYOCYTES

The unsatisfactory results of clinical trials with class-Ⅰ antiarrhythmic drugs have prompted a renaissance of interest in compounds with class-Ⅲ antiarrhythmic action. In the present, we have reevaluated the class-Ⅲ antiarrhythmic ef-