Effect of chlorpromazine and gossypol on Ca(2+)-ATPase activity in the microsomal membranes of rat testes.
The microsomal membranes isolated from rat testes have been found to contain a Mg(2+)-dependent and a Mg(2+)-independent Ca(2+)-ATPase. The enzyme activities were inhibited by two contraceptive drugs--gossypol and chlorpromazine. The inhibition by the former was affected by the presence of ligand(s) and not the substrate in the incubation medium, whereas ligand(s)/substrate did not affect the inhibition by chlorpromazine. This may be explained from the fact that the binding of chlorpromazine and ligand(s)/substrate to the enzyme are independent of each other whereas in case of gossypol the ligand(s) compete with the drug at the binding site of the enzyme.
Mazumder
B
B
Department of Chemistry, Bose Institute, Calcutta.
Sikdar
R
R
Sen
P C
PC
D000818:Animals; D017301:Ca(2+) Mg(2+)-ATPase / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000378:metabolism*; D002746:Chlorpromazine / Q000494:pharmacology*; D006072:Gossypol / Q000494:pharmacology*; D007425:Intracellular Membranes / Q000201:enzymology*; D007700:Kinetics; D008297:Male; D008861:Microsomes / Q000201:enzymology*; D051381:Rats; D013737:Testis / Q000201:enzymology*
D017301:Ca(2+) Mg(2+)-ATPase; D000252:Calcium-Transporting ATPases; D006072:Gossypol; D002746:Chlorpromazine