Abstract
The cardiovascular effects of prostaglandin E1 (PGE1) were studied in anesthetized dogs. It was found that the i.v. administration of 0.25 to 4.0 µg/kg of PGE1 decreased arterial pressure, left atrial pressure and left ventricular end-diastolic pressure, whereas heart rate, pulmonary arterial pressure, cardiac output and myocardial contractile force increased. Right atrial pressure remained essentially unchanged. The magnitude of the hemodynamic changes observed was essentially in proportion to the dose given. In addition, PGE1 increased significantly the maximum rate of isometric tension rise (dp/dt). It was also found that the i.a. administration of 0.1 µg/kg of PGE1 increased blood flows markedly and decreased peripheral resistances in the brachial, femoral, carotid, and renal arteries without any significant change in mean systemic arterial pressure and myocardial contractile force. Furthermore, the i.a. injection of PGE1 caused significant increases in both coronary arterial blood flow and myocardial contractile force without any change in mean systemic arterial pressure. The i.v. injection of 1 mg/kg of propranolol, which blocked completely the positive inotropic and chronotropic actions of norepinephrine (0.5 µg/kg) and the vasodilator action of isoproterenol (0.2 µg/kg) in vagotomized dogs, did not block the positive inotropic and vasodilator actions of PGE1 (4 µg/kg). The present study indicates that PGE1 induces multiple hemodynamic effects primarily through its potent direct vasodilator action on all peripheral vascular beds and indirectly through reflex sympathetic stimulation. In addition, PGE1 exerts a positive inotropic action on the heart. PGE1, in the doses given, does not appear to block the hemodynamic effects of norepinephrine in vagotomized dogs.
Footnotes
- Received October 20, 1966.
- Accepted January 9, 1967.
- © 1967 by The Williams & Wilkins Company
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