The specificity of prostaglandin E2 (PGE2) in reducing coronary vascular resistance: A comparison with adenosine.

Experiments were performed on the isolated, electrically driven guinea-pig heart, perfused at constant rate. All animals were pretreated with reserpine. Myocardial contractile force (MCF), coronary perfusion pressure (CPP) and myocardial oxygen consumption (QO2) were monitored continuously. Both adenosine (ADO) and PGE2 produced a concentration-dependent decrease in the CPP. The ED50 (50% of maximum response) was 2.1 +/- 0.6 X 10(-9)M for PGE2 but 40 +/- 7 X 10(-9)M for ADO (P less than 0.01) at 1.8 mM Ca(e). This coronary vasodilation was independent of the external Ca-concentration, which was varied between 0.55-9.0 mM. PGE2 had no effect on MCF or QO2 and the effect of ADO was only sligh…