Effects of Anti-Anginal Agents on Cyclical Reductions of Coronary Blood Flow

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Abstract
The effects of coronary vasodilating agents and .alpha.- and .beta.-adrenergic blocking agents on cyclical reductions of blood flow were studied in the partially occluded coronary artery of anesthetized dogs. Injections of nitroglycerin i.v. (50 .mu.g/kg), SG 75 [2-nicotinamide ethylnitrate] (150 .mu.g/kg), papaverine (1 mg/kg) and nicotinic acid (10 mg/kg) eliminated both cyclical reductions of flow and ST elevation (group 1). Nifedipine (10 .mu.g/kg), verapamil (500 .mu.g/kg), diltiazem (500 .mu.g/kg) and propranolol (500 .mu.g/kg) suppressed ST elevation, but did not eliminate cyclical reductions of flow (group 2). Dipyridamole (1 mg/kg) and phentolamine (500 .mu.g/kg) augmented both ST elevation and cyclical reductions of flow (group 3). ST elevation due to cyclical reductions of coronary blood flow was eliminated by spasmolytic actions of group 1 on coronary artery, was suppressed by negative chronotropic and/or inotropic actions of group 2 and was augmented by peripheral actions of group 3.