Effects of dauricine on physiologic properties of myocardium

Dauricine(D), the alkaloid isolated from Menispermum dauricum DC, possesses anti-arrhythmic and hypotensive actions. Its effects upon the physiologic properties of myocardium were studied on cat papillary muscles. 20-30 minutes after dauricine 32 μM was added, the contractility was decreased to 72±(SD)6%, and the duration-intensity curve was shifted to the right (p＜0.01) white the epinephrine concentration inducing automaticity was increased 4.6±3.1 times (p＜0.01), and the functional refractory period (FRP) was prolonged from 315±13 ms to 362±44 ms p＜0.02). The negative inotropism and automatism suggest that dauricine may be antagonistic to Ca++, while the decrease of excitability and the prolongation of FRP indicate that it may be due to its inhibition on Na+ current.