Impaired endothelium‐dependent relaxation of dog coronary arteries after myocardial ischaemia and reperfusion: prevention by amlodipine, propranolol and allopurinol

Abstract

Anaesthetized, open‐chest dogs were subjected to 60 min of left circumflex coronary artery occlusion followed by 90 min of reperfusion. Endothelium‐dependent and ‐independent relaxant responses of the isolated coronary arterial rings were then investigated. The endothelium‐dependent, acetylcholine‐induced relaxation of ischaemic/reperfused arterial rings was significantly attenuated in comparison to control rings (1.9 fold rightward shift, ischaemic/reperfused maximum relaxation = 57 ± 13% of control maximum relaxation; P < 0.05). In contrast, glyceryl trinitrate produced similar relaxant responses in control and ischaemic rings. Pretreatment of dogs with either amlodipine (3 μg kg−1 min−1, ..