Interaction of epoprostenol (PGI2) with vasoconstrictors on diameter of large coronary arteries of the dog

Abstract

The platelet release products thromboxane A2 (TxA2) and serotonin (5-HT) might contribute to coronary vasoconstriction in humans. We have examined the effects of a TxA2-like analogue (U46619), 5-HT, and epoprostenol (PGI2) on the left anterior descending coronary artery of the dog. Changes in diameter were measured by sonomicrometry during perfusion of the vessel with blood from a support dog, at constant flow and distal resistance. Intra-arterial infusions of 5-HT (0.01-1 μ.mol/L) and U46619 (0.003-0.1 μmol/L) reduced external diameter of the artery (about 2.0 mm) by 0.12 mm and 0.16 mm, respectively. Intra-arterial PGI2 (0.01-0.1 μmol/L) increased the diameter of the artery (by 0.08 mm) an..