Inhibitory effects of cyproheptadine on calmodulin activated Ca (2+) -ATPase activity of rabbit erythrocyte membranes
Xin, H.B.; Zhang, B.H.
Zhongguo Yao Li Xue Bao 14(Suppl): S5-S7
1993
ISSN/ISBN: 0253-9756 PMID: 8010076 Document Number: 407286
Membranes prepared from rabbit erythrocyte hemolyzed in isosmotic imidazole (151 mmol cntdot L-1, pH 7.4) buffer showed an enhancement of calmodulin (CaM) activated Ca-2+-ATPase activity compared with the membrane prepared in hypotonic imidazole (10 mmol cntdot L-1, EGTA 1 mmol cntdot L-1, pH 7.4) buffer. The Ca-2+-ATPase activity of the former (activated-calmodulin) was inhibited by cyproheptadine (Cyp) with IC-50 75 mu-mol cntdot L-1 (95% confidence interval was 18-319 mu-mol cntdot L-1, tau = 0.9118), while the Ca-2+-ATPase activity of the latter (inactivated) was hardly influenced by Cyp. The results suggest that cyproheptadine antagonizes CaM, and its actions of the calcium antagonism - and the, anti-myocardial injury may, at least partially, be related to its CaM antagonism.