[Inhibitory effects of cyproheptadine on calmodulin activated Ca(2+)-ATPase activity of rabbit erythrocyte membranes].
Membranes prepared from rabbit erythrocyte hemolyzed in isosmotic imidazole (151 mmol.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.L-1, EGTA 1 mmol.L-1, pH 7.4) buffer. The Ca(2+)-ATPase activity of the former (activated-calmodulin) was inhibited by cyproheptadine (Cyp) with IC50 75 mumol.L-1 (95% confidence interval was 18-319 mumol.L-1, r = 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.
Xin
H B
HB
Department of Pharmacology, School of Basic Medical Sciences, Beijing Medical University, China.
Zhang
B H
BH
D000818:Animals; D000252:Calcium-Transporting ATPases / Q000378:metabolism*; D002147:Calmodulin / Q000502:physiology; D003533:Cyproheptadine / Q000494:pharmacology*; D004910:Erythrocyte Membrane / Q000201:enzymology*; D011817:Rabbits
D002147:Calmodulin; D003533:Cyproheptadine; D000252:Calcium-Transporting ATPases