Effect of Phenoxybenzamine and Propranolol on Myocardial Reactive Hyperaemia in Fibrillating Canine Heart

In order to evaluate whether alpha and beta adrenergic mechanisms participate in the coronary reactive hyperaemia, effects of phenoxybenzamine (10 mg per kg b.w.) or propranolol (2 mg per kg b.w.), or phenoxybenzamine + propranolol on reactive hyperaemic responses following 15, 30, 60 and 120 s occlusions of left coronary vessels were investigated on isolated fibrillating, blood-perfused dog heart preparations. Hearts were either perfused at constant pressure or at constant volume on the basal perfusion pressure of 150 mm Hg.