The effects of carbocromene, 4 mg/kg intravenously, prior to coronary artery occlusion plus 40 μg/kg/min during coronary artery occlusion and reperfusion on ventricular fibrillation threshold (VFT) were studied in pentobarbital-anesthetized open-chest dogs and compared to controls receiving saline. Coronary artery occlusion decreased VFT by 46 ± 4% (mean ± SEM, p < 0.02) in controls and by 22 ± 3 % in drug-treated animals. Reperfusion of the occluded artery decreased VFT by 83 ± 7% (p < 0.01) in controls and by 47 ± 5% in carbocromene-treated hearts (p < 0.02). Hemodynamics did not change in the drug group during coronary artery occlusion. In controls, blood pressure and dP/dt_max decreased while heart rate, end-diastolic pressure and ST-T segments increased significantly during both coronary artery occlusion and reperfusion. The underperfused, ischemic region was assessed by staining with Evans blue and involved 34 ± 3% of the left ventricular mass in controls but only 27 ± 3% in carbocromene-treated hearts (p < 0.05). These results indicate protective effects of carbocromene on ventricular vulnerability in canine hearts during coronary artery occlusion and subsequent reperfusion.

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