Effects of tetrandrine on inotropic and toxic actions of cardiac glycosides and its relation to extracellular calcium
Abstract
The effects of tetrandrine (T) or Ca2+ on inotropic and toxic actions of 2 cardiac glycoside preparations, divasid and ouabain, were studied with isolated left atria of rabbits.
Tetrandrine at a low but still hypotensive effective concentration (4.8μM) prolonged PET and reduced the toxicity of the 2 preparations. No effect on the degree of contraction amplitude increment was observed. These effects of tetrandrine are not attributable to its negative inotropic action. Since they were antagonized by Ca2+, it may be assumed that tetrandrine is a calcium antagonist.
Keywords:
Tetrandrine at a low but still hypotensive effective concentration (4.8μM) prolonged PET and reduced the toxicity of the 2 preparations. No effect on the degree of contraction amplitude increment was observed. These effects of tetrandrine are not attributable to its negative inotropic action. Since they were antagonized by Ca2+, it may be assumed that tetrandrine is a calcium antagonist.