Quantitation of isoproterenol-induced myocardial necrosis with 3H-tetracycline.

Methods currently used to quantitate myocardial damage and necrosis produced by chemicals are usually time consuming and subjective. These studies were conducted to evaluate the utility of 3H-tetracycline as a means of quantitating myocardial necrosis produced by isoproterenol. Male, Sprague-Dawley derived rats (180-200 g) were treated with (+/-)-isoproterenol HCl (0.1-100 mg/kg, s.c.) or equivalent volumes of saline. After 90 minutes, all rats received 50 uCi/kg of 3H-tetracycline. Rats were sacrificed 3 hours after 3H-tetracycline administration and the hearts were removed and rinsed free of blood. The degree of radioactivity of the heart as determined by liquid scintillation counting was directly proportional to the dose of isoproterenol. Propranolol pretreatment decreased the accumulation of radioactivity in a dose-dependent fashion. Determination of 3H-tetracycline accumulation appears to be a rapid and reliable method for quantitating isoproterenol-induced myocardial necrosis.