Comparison of contractile responses to 5‐hydroxytryptamine and sumatriptan in human isolated coronary artery: synergy with the thromboxane A2‐receptor agonist, U46619

Abstract

The interaction between the thromboxane A2 receptor agonist, U46619 and two 5‐hydroxytryptamine (5‐HT) receptor agonists, the non‐selective, naturally occurring agonist, 5‐HT and the selective 5‐HT1‐like agonist, sumatriptan were studied in human epicardial coronary arteries in vitro. Coronary artery rings (2–4 mm in diameter) were prepared from epicardial arteries from explant hearts of patients undergoing heart transplant (cardiomyopathy, n = 13; ischaemic heart disease, n = 10) and unused donor hearts (n = 5). Each ring of artery was set at optimal resting conditions to record changes in isometric force. The majority of artery rings developed phasic, rhythmic contractions either spontaneo..