[Effect of oxyphenamone, a new inodilator, on cardiac hemodynamics in normal rat, cat and dog].

For studying the cardiotonic and vasaodilating effect of oxyphenamone in vivo, cardiac hemodynamic variables of anesthetized normal rats, cats and dogs were determined with a polygraph and electromagnetic flowmeters. Intravenous injection of oxyphenamone (0.5-10 mg.kg-1) dose-dependently decreased the mean arterial pressure and systemic vascular resistance moderately and increased cardiac output, myocardial contractile force and +/- dT/dtmax. The blood flow of coronary and femoral arteries increased markedly and their vascular resistance decreased but the blood flow and vascular resistance of cerebral artery did not change. Some species differences were observed in the effect of oxyphenamone on heart rate (HR) and left ventricular pressure (LVP). Oxyphenamone did not influence the HR and LVP in normal cats. It decreased the HR, left ventricular systolic pressure (LVSP) and +/- dP/dtmax, while did not affect the left ventricular end diastolic pressure (LVEDP) in rats. In contrast, administration of oxyphenamone to dogs increased LVSP and +/- dP/dtmax markedly and diminished LVEDP slightly. Oxyphenamone decreased HR slightly at lower dosage (1 and 3 mg.kg-1), but increased heart rate moderately at high dose (6 mg.kg-1) in dogs. These indicate that oxyphenamone has cardiotonic and vasodilating effects in vivo. Whether the effects of oxyphenamone on cardiac hemodynamics would be useful for the treatment of heart failure should be evaluated further.