VENTRICULAR EXTRASYSTOLES INDUCED BY EPINEPHRINE, NICOTINE, ETHANOL, AND VASOPRESSIN IN DOGS WITH MYOCARDIAL LESIONS

In a group of normal conscious dogs, neither intravenous administration of vasopressin (0.4 unit/kg), epinephrine (4 μg/kg), 50% ethanol (2 ml/kg) nor oral administration of 30% ethanol (6-7 ml/kg) caused ventricular extrasystoles. In a second group of dogs, myocardial necrosis produced by the subcutaneous injection of 1 mg/kg isoproterenol (a sympathomimetic amine) or by ligation of the left anterior descending coronary artery evoked ventricular extrasystoles. This electrocardiographic abnormality disappeared within a few days, but thereafter, during the histologic stage of necrosis, the administration of the aforementioned agents elicited paroxysmal ventricular extrasystoles. Vasopressin elicited this effect even during the stage of resorption. Electrocardiographic changes were not seen in dogs dosed with 0.5 mg/kg isoproterenol, but paroxysmal extrasystoles following the administration of vasopressin revealed the presence of cardiac injury. These findings indicated the usefulness of the vasopressin response for cardiotoxicity testing. These results further implied an alteration in drug sensitivity of the damaged myocardium, a finding of toxicologic interest. © 1969.