Effect of propranolol and nitroglycerin plus methoxamine on transmural creatine kinase activity after acute coronary occlusion

Transmural creatine kinase activity was determined 5 hours after acute occlusion of the left anterior descending coronary artery in 27 open chest anesthetized dogs. In seven dogs, propranolol, 2 mg/kg, was given intravenously over a 10 minute period 10 minutes after occlusion. In 10 dogs, nitroglycerin, 300 μg/min, was infused intravenously for 1 hour 10 minutes after occlusion. Methoxamine, 300 to 500 μg, was administered to return blood pressure and heart rate to prenitroglycerin levels. In untreated dogs, there was a distinct transmural gradient of creatine kinase activity in the ischemic region from subepicardium to subendocardium: nonischemic subepicardium 1,187 ± 50 international units (IU)/g versus ischemic subepicardium 1,054 ± 46 IU/g and nonischemic subendocardium 1,170 ± 53 IU/g versus ischemic subendocardium 766 ± 42 IU/g, respectively. Administration of propranolol did not affect the transmural creatine kinase gradient after 5 hours of occlusion. In contrast, nitroglycerin plus methoxamine significantly ( P