Catecholamine Metabolism in Experimental Hypertension in the Rat

Abstract

The role of catecholamines was investigated in uninephrectomized Sprague-Dawley male rats made hypertensive by administration of desoxycorticosterone and a high salt diet. The accumulation of tritiated norepinephrine and the endogenous norepinephrine levels were measured in the various organs. The content of endogenous norepinephrine and the accumulation of 3 H-norepinephrine 1 hour after its injection were reduced in the heart, spleen, intestine, skeletal muscle, and kidney of hypertensive rats as compared to controls. Simultaneously, an increase in total 3 H-metabolites was also found in the hypertensive animals. A highly significant inverse relation was established between the level of blood pressure and the accumulation of 3 H-norepinephrine or endogenous norepinephrine levels in the heart. The abnormalities observed in the disposition of exogenously administered and endogenous norepinephrine do not appear to be secondary to a change in the distribution of cardiac output to the various organs. Since the initial uptake was normal in the hypertensive rats, the reduced capacity to accumulate norepinephrine seems to be related to a defect in the storage of norepinephrine.