Study of Antagonistic Effect of Total Alkaloids of Corydalis Amabilis Migo on Calcium
Liu Min Fang Gaohong (Department of pharmacology, Jiangxi Medical College)
Corydalis amabilis Migo total alkaloids (COAMTA)has been demonstrated to dilate the isolated rabbit aortic strips which were in contraction evoked by NE, high K and CaCl_2. The cumulative dose-response curves for NE, KCl and CaCl_2 shifted to the right, and their maximal responses were depressed, The PD'_2 were 4.78, 4.61 and 4.45 respectively. COAMTA inhibited both fast and transitory contraction (Ca_1~(++)-dependent) response evoked by NE in Ca~(++)-free medium and the slow sustained contraction (Ca_0~(++)-dependent) response after the supplement of CaCl_2. In the isolated rabbit hearts, 5×10~(-5)g COAMTA showed negative inotropic effect and antagonized the positive inotropic effect of 2×10~(-5)g GaCl_2, so it further proved COAMTA antagonized the action of Ca~(++). In addition, COAMTA prolonged the time of rabbit plasma calcium recovery. These results suggested that COAMTA induced relaxation on vascular smooth muscle might result from its antagonistic effect to Ca~(++) and that the mode of this antagonism differed from that of Ver. It is possible that these 2 drugs interfere with 2 different transmembrane Ca~(++) channels.