Effects of aldosterone and spironolactone on the isolated perfused rat heart.

Aldosterone antagonists are used in the treatment of hypertension. However, the cardiac influences of aldosterone and its antagonists have not been thoroughly investigated. In the present study, we investigated the effects of aldosterone and spironolactone on an isolated rat working heart model. Aldosterone (10(-8) mol/l) decreased the coronary flow and increased aortic flow and cardiac output. Spironolactone (10(-5) mol/l) inhibited these effects. These results suggest that aldosterone directly influences the cardiac function. Spironolactone appears able to inhibit the adverse cardiac effects of aldosterone. The exact mechanisms remain to be elucidated, but the early effects of aldosterone under our experimental conditions on the functional parameters of the heart suggest a nongenomic response including activation of receptors different from those transmitting genomic steroid actions.