[Effects of oxyphenamone on myocardial ischemia in cats and rats]

To study the therapeutic effects of oxyphenamone, a novel inodilator, on myocardial ischemia.

The cardiac hemodynamic variables in cats with acute myocardial infarction induced by occlusion of the left anterior descending coronary artery (LAD) were recorded with a physiological polygraph and electromagnetic flowmeter. A model of myocardial necrosis induced by subcutaneous injection of isoproterenol was used for evaluating the effects of drugs on myocardial enzymes and morphological change.

Intravenous injection of oxyphenamone (2 - 8 mg x kg(-1)) dose-dependently decreased heart rate, mean arterial pressure, vascular resistance and the parameters of myocardial oxygen consumption (tension time index, TTI) in cats with myocardial infarction. It increased myocardial contractile force and cardiac output transiently but showed no influence on the left ventricular pressure and cardiac work. The changes of myocardial morphology, creatine phosphate kinase (CPK), malodialdehyde (MDA) and serum glutamic-oxaloacetic transaminase (GOT) induced by isoproterenol in rats were diminished by intraperitoneal injection of oxyphenamone (4 - 8 mg x kg(-1)).

By the examination of the cardiac hemodynamics, myocardial enzymes and morphology, it showed that the myocardial damage induced by ischemia or beta-agonist can be antagonized markedly by oxyphenamone, indicating that oxyphenamone may be beneficial for the treatment of myocardial infarction.