Effects of tetrandrine on cat papillary muscle
Abstract
Tetrandrine (T), isolated from the root of Stephania tetrandra S. Moore, possessed antihypertensive and antiarrhythmogenic effects. This paper studied its direct action upon the contractility, automaticity, excitability and refractory period of cat papillary muscle.
1. 32 microM decreased the contractility, +/-dT/dtmax and automaticity induced by adrenaline and prolonged the functional refractory period (FRP), but exerted no influence upon the excitability.
2. The decrease in automaticity and prolongation of FRP were thought to be relevant to its antiarrhythmic action
3. The negative inotropic and automaticitic effects suggested that tetrandrine might be antagonistic to Ca2+.
Keywords:
1. 32 microM decreased the contractility, +/-dT/dtmax and automaticity induced by adrenaline and prolonged the functional refractory period (FRP), but exerted no influence upon the excitability.
2. The decrease in automaticity and prolongation of FRP were thought to be relevant to its antiarrhythmic action
3. The negative inotropic and automaticitic effects suggested that tetrandrine might be antagonistic to Ca2+.