Effects of tetrandrine on action potential and contraction of isolated guinea pig papillary muscle
Zong, X.G.; Jin, M.W.; Xia, G.J.; Fang, D.C.; Jiang, M.X.
Zhongguo Yao Li Xue Bao 4(4): 258-261
1983
ISSN/ISBN: 0253-9756 PMID: 6230871 Document Number: 212480
The effects of tetrandrine on action potential and contraction were studied in isolated guinea pig papillary muscles in normal and K+-rich Tyrode's solution. Tetrandrine produced concentration-dependent negative inotropic effects and shortened APD20 and APD90, but resting potential and amplitude of action potential were not influenced. An excitation-concentration uncoupling was seen. Tetrandrine decreased the amplitude of Ca2+-mediated slow action potential induced by high K+. These results are in contrast with those of quinidine and indicate that tetrandrine can be considered as a blocker of the slow channel.