INFLUENCE OF ADRENALECTOMY ON THE SYNTHESIS OF NOREPINEPHRINE IN THE RAT HEART

¹ Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, Virginia

The influence of bilateral adrenalectomy on the synthesis of norepinephrine (NE) in the rat heart was determined by three independent methods 6 to 9 days after the operation. Two of the methods involved estimating turnover rates by: 1) measuring the decline of cardiac NE after inhibition of tyrosine hydroxylase with -methyl-p-tyrosine (-MPT) and 2) measuring the decline in specific activity of H³-NE in the heart after its i.v. administration. The third method involved measuring the amount of C¹⁴-NE formed in the heart after the i.v. administration of C¹⁴-tyrosine. Results obtained from all three methods showed a significant increase in the synthesis rate of NE in hearts from adrenalectomized rats over that obtained in normal or sham-operated animals. Hydrocortisone, desoxycorticosterone acetate and hexamethonium all prevented the accelerated synthesis rate. Adrenalectomy did not alter the uptake of H³-NE in the isolated perfused heart but did result in a significant increase in myocardial monoamine oxidase activity. it is suggested that the increase in synthesis rate of NE and in monoamine oxidase activity is the result of a reflexly mediated increase in sympathetic nerve activity secondary to a decrease in blood pressure from adrenalectomy.

This article has been cited by other articles:

				R. M. Sapolsky, L. M. Romero, and A. U. Munck How Do Glucocorticoids Influence Stress Responses? Integrating Permissive, Suppressive, Stimulatory, and Preparative Actions Endocr. Rev., February 1, 2000; 21(1): 55 - 89. [Abstract] [Full Text]