Calmodulin reduces ouabain-sensitive ATPase of cardiac sarcolemmal membranes: high reduction in spontaneously hypertensive rats.
Calmodulin and calcium effects on cardiac ouabain-sensitive adenosine triphosphatase (ATPase) activity were studied in young spontaneously hypertensive rats (SHR) and in their normotensive control Wistar-Kyoto rats (WKY). Cardiac sarcolemmal membranes from SHR showed significantly higher ouabain-sensitive ATPase activity than membranes from WKY rats. This activity was unaffected by calmodulin or calcium alone. However, when both calmodulin and calcium were added, ouabain-sensitive activity was significantly reduced without changes in the total ATPase activity. The calcium-dependent calmodulin effect was dose-dependent and greater in SHR than in WKY membranes. An altered interaction between the calcium-calmodulin system and sodium handling by the plasma membrane in SHR may play a role in the pathogenesis of hypertension.
D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002147:Calmodulin / Q000494:pharmacology*; D006321:Heart / Q000187:drug effects; D006973:Hypertension / Q000201:enzymology*; D066298:In Vitro Techniques; D009206:Myocardium / Q000201:enzymology*; D010042:Ouabain / Q000494:pharmacology; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D012508:Sarcolemma / Q000187:drug effects / Q000201:enzymology
D002147:Calmodulin; D010042:Ouabain; D000251:Adenosine Triphosphatases; D002118:Calcium