Prostacyclin (PGI2) induces coronary vasodilatation in anaesthetised dogs
Abstract
Prostacyclin (PGI2), the predominant metabolite of arachidonic acid in isolated hearts, relaxes strips of bovine coronary artery and is a potent vasodilator in isolated perfused hearts. We have examined the actions of prostacyclin on coronary blood flow in open chest dogs anaesthetised with chloralose. An electromagnetic flow probe was fitted to the left circumflex artery and phasic coronary flow, mean coronary flow (a measure of coronary volume flow over 4 s intervals), and coronary vascular resistance were recorded together with aortic pressure and heart rate. Intravenous infusion of prostacyclin (0.05 to 1.0 microgram.kg.1.min.1), reduced coronary vascular resistance and aortic pressure according to dose, but had only small effects on phasic coronary flow or mean coronary flow. Both tachycardia and bradycardia occurred during infusion of prostacyclin, but 6-oxo-prostaglandin F1alpha (infused at 10 micrograms.kg-1.min-1), the stable degradation produce of prostacyclin, had no cardiovascular effects. The coronary vasodilator effects of prostacyclin were clear when it was injected into the left circumflex artery via a fine catheter distal to the flow probe. Prostacyclin (0.05 to 0.5 microgram) increased phasic coronary flow and...Continue Reading
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