EFFECTS OF DAURICINE ON THE DOSE—EFFECT RESPONSE OF ISOPRENALINE AND Ca²⁺ AND THE ELECTRO-MECHANIC ACTIVITY IN CAT PAPILLARY MUSCLE

Dauricine (D), an akaloid, isolated from Menispermum dauricum DC., was reported to have antiarrhythmic and hypotensive effects. The effects of dauricine on the dose—effect response of isoprenaline and Ca²⁺ and the electro-mechanic activity in cat papillary muscle were studied and compared with tetrandrine and/or verapamil, propranolol and quinidine.1. Dauricine 8×10^-5 M decreased and shifted the isoprenaline(ISO)dose—response curve to the right non-parallelly. It appears that dauricine is similar to tetrandrine and verapamil, but different from propranolol in this respect.2. Dauricine, as tetrandrine and verapamil, showed dualistic action in Ca²⁺-antagonism.3. Effect of dauricine on the electro-mechanic activity: it depressed and widened the R wave, prolonged R-T of the surface electromyogram of the papillary muscle, and its inotropic action was analogous to that of tetrandrine. It seems that dauricine possesses not only Ca-antagonistic but also "quinidine-like" action.