Trifluoperazine inhibition of calmodulin-sensitive Ca2+ -ATPase and calmodulin insensitive (Na+ +K+)- and Mg2+ -ATPase activities of human and rat red blood cells.
Trifluoperazine dihydrochloride-induced inhibition of calmodulin-activated Ca2+ -ATPase and calmodulin-insensitive (Na+ +K+)- and Mg2+ -ATPase activities of rat and human red cell lysates and their isolated membranes was studied. Trifluoperazine inhibited both calmodulin-sensitive and calmodulin-insensitive ATPase activities in these systems. The concentration of trifluoperazine required to produce 50% inhibition of calmodulin-sensitive Ca2+ -ATPase was found to be slightly lower than that required to produce the same level of inhibition of other ATPase activities. Drug concentrations which inhibited calmodulin-sensitive ATPase completely, produced significant reduction in calmodulin-insensitive ATPases as well. The data presented in this report suggest that trifluoperazine is slightly selective towards calmodulin-sensitive Ca2+ -ATPase but that it is also capable of inhibiting calmodulin-insensitive (Na+ +K+)-ATPase and Mg2+ -ATPase activities of red cells at relatively low concentrations. Thus the action of the drug is not due entirely to its interaction with calmodulin-mediated processes, and trifluoperazine cannot be assumed to be a selective inhibitor of calmodulin interactions under all circumstances.
D000251:Adenosine Triphosphatases / Q000097:blood*; D000818:Animals; D017301:Ca(2+) Mg(2+)-ATPase; D002135:Calcium-Binding Proteins / Q000494:pharmacology*; D000252:Calcium-Transporting ATPases / Q000097:blood*; D002147:Calmodulin / Q000494:pharmacology*; D004910:Erythrocyte Membrane / Q000201:enzymology; D004912:Erythrocytes / Q000201:enzymology*; D006801:Humans; D007700:Kinetics; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D000254:Sodium-Potassium-Exchanging ATPase / Q000097:blood*; D014268:Trifluoperazine / Q000494:pharmacology*
D002135:Calcium-Binding Proteins; D002147:Calmodulin; D014268:Trifluoperazine; D000251:Adenosine Triphosphatases; D017301:Ca(2+) Mg(2+)-ATPase; D000252:Calcium-Transporting ATPases; D000254:Sodium-Potassium-Exchanging ATPase