Effects of dauricine on the dose-response relationship of isoproterenol and calcium and on the electro-mechanical activity in cat papillary muscles

Abstract

Our previous reports described the anti-arrhythmic and hypotensive actions of dauricine (Dau), an alkaloid isolated from Menispermum dauricum DC. In the present paper we made a study of its effects on isoproterenol and calcium-mediated dose-response relationships and on the electro-mechanical activity in cat papillary muscles, and compared its actions with those of tetrandrine and/or verapamil, propranolol, quinidine. The results obtained are summarized as follows.

1.	Dau 8 x 10-5 M shifted the isoprenaline dose-response curve to the right with decrease of its maximum effect, in which it resembled tetrandrine 10-5 M, verapamil 5 x 10-7 M, but differed from propranolol.
2.	Dau, like tetrandrine and verapamil, showed dualism in calcium antagonism.
3.	Effect of Dau on the electro-mechanical activity: It depressed and widened the R wave, prolonged R-T interval of the surface electrogram of cat papillary muscles, and its inotropic action was analogous to that of tetrandrine. Dau seemed to possess not only calcium antagonistic, but also “quinidine-like” action.

Keywords

dauricine / tetrandrine / iproveratril / cat papillary muscle / calcium antagonist

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