ACTIONS OF PROSTAGLANDIN E2 ON MYOCARDIAL MECHANICS, CORONARY VASCULAR RESISTANCE AND OXYGEN CONSUMPTION IN THE GUINEA‐PIG ISOLATED HEART PREPARATION

Abstract

1 In isolated, electrically driven (3 Hz) hearts of guinea-pigs the action of prostaglandin E₂ on left ventricular pressure (LVP), oxygen consumption (Qo₂) and coronary vascular resistance (CVR) was studied by establishing cumulative concentration-response curves. The hearts were perfused at a constant flow (10 ml/min) with Tyrode solution (Ca⁺⁺ 1.8 mM) at 32° C. 2 Under control conditions prostaglandin E₂ (2.86 × 10⁻¹¹ − 1.43 × 10⁻⁷ M) decreased LVP, Qo₂ and CVR in a concentration-dependent manner by maximally 27, 18 and 38%, respectively (P < 0.05). 3 After reserpine pretreatment there were lower initial values for all parameters measured. The effect of prostaglandin E₂ on LVP and Qo₂ was abolished, but CVR was further diminished, depending on the concentration. 4 The results seem to support the hypothesis of an interaction of prostaglandin E₂ with endogenous catecholamines as far as the effects on LVP and Qo₂ are concerned. In contrast, prostaglandin E₂ seems to have a direct action on CVR, which is independent of the presence of catecholamines.