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The effect of a new cardioselective beta adrenergic antagonist, bevantolol (CI-775), on regional myocardial blood flow and contractile function distal to a severe flow-limiting stenosis of the left circumflex coronary artery was studied in open-chest dogs. Bevantolol (1 mg/kg, i.v.) or saline was administered 30 min after production of left circumflex stenosis sufficient to reduce resting coronary blood flow and contractile force approximately 40%. Regional myocardial blood flow and contractile force were measured with radiolabeled microspheres and Brodie—Walton strain gauge arches, respectively. No significant changes were observed in the saline-treated group. Following bevantolol treatment subendocardial blood flow (1.30 ± 0.29 to 0.93 ± 0.19 ml/min/g) and contractile force decreased (11.4 ± 4.4%) significantly (p < 0.05) in nonischemic myocardium. Subendocardial blood flow (0.59 ± 0.14 to 0.81 ± 0.14 ml/min/g) and contractile force increased (29.3 ± 3.6%) significantly (p < 0.05) in ischemic myocardium. These results suggest that bevantolol produces a favorable redistribution of flow to ischemic subendocardium. The increase in flow results in an improvement of contractile function in the ischemic region.