The carduc effects of THB were studied in uolated rught and left atrual prepa-rations from guinea pigs.In spontaneously beating right atrua,TH B(1-56.3μmal/L caused brady-card ia,which was not prevented by atropine(1...The carduc effects of THB were studied in uolated rught and left atrual prepa-rations from guinea pigs.In spontaneously beating right atrua,TH B(1-56.3μmal/L caused brady-card ia,which was not prevented by atropine(1μmol/L).The time-effect curve of right atria on 4 mmul/L CaClz was markedly decreased by TIB.Tl B shifted the concentratwn-effect curve of iso to the right,and the maximum effect of Iso was clearly reduced.The PD2'was 5.32.For this reasun,the bradycard iae effect of TlI B mught be related to antogonism to Ca'+transport and non-competitme,block ofβ-adrenoceptur.Tll B pruduced negative inotropu effect.A decrease in trans membrane influz of Ca²+and inhibution of intracelluar calcium release mrght contribute to this action.展开更多
文摘The carduc effects of THB were studied in uolated rught and left atrual prepa-rations from guinea pigs.In spontaneously beating right atrua,TH B(1-56.3μmal/L caused brady-card ia,which was not prevented by atropine(1μmol/L).The time-effect curve of right atria on 4 mmul/L CaClz was markedly decreased by TIB.Tl B shifted the concentratwn-effect curve of iso to the right,and the maximum effect of Iso was clearly reduced.The PD2'was 5.32.For this reasun,the bradycard iae effect of TlI B mught be related to antogonism to Ca'+transport and non-competitme,block ofβ-adrenoceptur.Tll B pruduced negative inotropu effect.A decrease in trans membrane influz of Ca²+and inhibution of intracelluar calcium release mrght contribute to this action.
