Effect of prostaglandins on rat heart sarcolemmal ATPases

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Abstract
The ability of prostaglandins (PG) D2, E1, E2, F2α and I2 (2.8 × 10−11 M to 2.8 × 10−7 M) to modify Ca2+, Mg2+ and (Na+ + K+)-ATPase activities of rat heart sarcolemmal membrane fractions was examined. Administration of PGE2, PGF2α, and PGI2 reduced basal (Na+ + K+)-ATPase activity by up to 30, 80, and 80%, respectively. PGE1 and PGD2 were ineffective at any concentration. Neither Mg2+-ATPase nor Ca2+-ATPase was affected by PG treatment. Kinetic analysis revealed that the (Na+ + K+)-ATPase activity reducing ability of PGE2, PGF2α and PGI2 was of a complex nature involving a reduction in Vmax and an elevation of the respective K values for either substrate or activator. These results demonstrate that some PG's are potent inhibitors of rat heart (Na+ + K+)-ATPase. These PG's produced varied inotropic influences on isolated heart preparations and it is uncertain whether their myocardial actions are dependent on enzyme inhibition.