ARTERIAL-HYPERTENSION AND PULMONARY-EDEMA INDUCED BY CATECHOLAMINES IN UNANESTHETIZED RATS

The mechanism of pulmonary edema induced by catecholamines in unanesthetized rats was investigated. Intravenous injection of 40 μg/kg of adrenaline or noradrenaline induced systolic and diastolic arterial hypertension, sinus bradycardia, A-V block, ventricular ectopic beats, apnea followed by tachypnea and pulmonary edema. ST segment displacements were observed only in rats injected with adrenaline. The peak of the mean arterial pressure and the simultaneous bradycardia were not significantly different in these groups, but the lung/body index was 89% larger in adrenaline injected rats than in those injected with noradrenaline. The pulmonary edema induced by 20 μg/kg of adrenaline was significantly smaller than that evoked by 40 μg/kg. The injection of a non-edematogenic dose of adrenaline (10 μg/kg) in atropine-treated rats induced pulmonary edema, with an increase of 100% in the lung/body index. Atropine also increased by 50% the lung/body index of rats injected with noradrenaline. It seems that the effects of atropine are due to blockade of bradycardia. In urethane-anesthetized rats, 40 μg/kg of adrenaline induced a smaller hypertensive effect and no pulmonary edema. It is suggested that the pulmonary edema induced by adrenaline and noradrenaline in unanesthetized rats depends, in part, on a left heart failure and that tachypnea recorded in rats with edema could be related to stimulation of vagal receptors in the lungs. © 1979 The Italian Pharmacological Society.