Affiliation:
1. Groupe de Recherche sur le Systeme Nerveux Autonome, Faculte dePharmacie, Universite de Montreal, Quebec, Canada.
Abstract
The present study was designed to test whether endothelin (ET) A and/or B receptors in the adrenal medulla are functionally involved in ET-1-induced catecholamine (CA) release in anesthetized dogs. ET-1 was locally infused into the gland via the left adrenolumbar artery. Plasma CA in adrenal venous and aortic blood was determined by a high-performance liquid chromatography method. In the control group, the local infusion of ET-1 (0.5 microg, 0.4 microM) resulted in a significant increase in CA output. In the presence of a low dose of BQ-123 (5 microg, 16.4 microM), the ET-1-induced CA response was significantly attenuated by approximately 80%. With a high dose of BQ-123 (50 microg, 164 microM), the CA response was further blocked by approximately 95%. This inhibition was significantly greater than that obtained with the low dose of BQ-123. By contrast, a low dose of BQ-788 (5 microg, 15.1 microM) did not significantly affect the CA response. With a high dose of BQ-788 (50 microg, 151 microM), the CA response was only partially inhibited by approximately 70%. The results indicate that BQ-123 significantly inhibited ET-1-induced adrenal CA release in a dose-dependent manner. With the low doses, the CA response was markedly inhibited by BQ-123 but remained unchanged in the presence of BQ-788. Moreover, the high dose of BQ-123 virtually abolished the CA response, whereas BQ-788 failed to do so within the dose range tested. The present study suggests that the ET(A) receptor may play a predominant role in mediating the ET-1-induced CA secretion in the canine adrenal gland in vivo, although the possible involvement of the ET(B) receptor could not completely be excluded under the present experimental conditions.
Publisher
American Physiological Society
Subject
Physiology (medical),Physiology
Cited by
25 articles.
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