Simultaneous evaluation of medullary secretory functions of normal and acutely denervated adrenals

Abstract

Adrenal medullary secretory function of the right innervated gland was simultaneously compared with that of contralateral acutely denervated gland in anesthetized dogs. During bilateral carotid artery occlusion (BCO), output (in ng/min) from right innervated gland of epinephrine and norepinephrine increased from 86.6 +/- 33.0 and 34.4 +/- 15.1 to 280.8 +/- 86.7 (P less than 0.01, n = 7) and 104.4 +/- 40.6 (P less than 0.01, n = 7), respectively. By contrast, epinephrine output from left denervated gland increased only slightly (P less than 0.05), and norepinephrine did not increase significantly. Net catecholamine output from left denervated gland was markedly attenuated by approximately 90% (P less than 0.01, n = 7) compared with that from right innervated gland. During BCO in the second group of dogs, catecholamine output from sham-denervated left gland increased significantly (P less than 0.01, n = 7) to an extent slightly lower than that observed in right innervated gland. In the third group, intravenous injections of dimethylphenylpiperazinium (5 and 15 micrograms/kg) resulted in a dose-dependent increase (P less than 0.05, n = 7) in catecholamine output from both right innervated and left denervated gland. The results indicate that the present procedure of acute surgical adrenal denervation can eliminate the centrally mediated adrenal response, whereas the medullary secretory response to blood-borne substances remains intact. This model may be a useful tool for studying neuronal and humoral medullary secretory functions in vivo under various experimentally induced stress conditions.