| 1. | Tetrandrine was found to decrease the contractility, ±dT/dtmax and automaticity and prolong the functional refractory period of cat papillary muscle, but it exerted no influence on its excitability. |
| 2. | The above results are in accordance with those we obtained previously in guinea pig atrium. |
| 3. | The negative inotropic and automaticitic effects indicate that tetrandrine might be a calcium influx blocker like verapamil. |
From the fruit of Rhododendron molle G.Don an active principle has been isolated, which possesses antihypertensive and bradycardiac actions and has been used clinically for severe hypertension with good results. The active principle rhomotoxin has been proved to be the same as rhodojaponin-III by physical and chemical identification.