Vierhapper H. Effect of endothelin-1 in man--impact on basal and stimulated concentrations of luteinizing hormone, follicle-stimulating hormone, thyrotropin, growth hormone, corticotropin, and prolactin with and without pretreatment with nifedipine.
Metabolism 1996;
45:658-61. [PMID:
8622612 DOI:
10.1016/s0026-0495(96)90039-6]
[Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
In healthy men, intravenous (IV) endothelin-1 suppresses the growth hormone (GH)-releasing hormone (GHRH)-stimulated increase in GH and prolactin (PRL) and augments corticotropin (ACTH)-releasing factor (CRF)-stimulated secretion of ACTH. Since some actions of endothelin-1 on pituitary function in vitro are antagonized by calcium channel antagonists, we have studied the effect of pretreatment with oral nifedipine (10 mg, given before infusion of endothelin-1 or vehicle) on basal and stimulated concentrations of pituitary hormones in a group of healthy men (N = 6). The augmentative effect of endothelin-1 on CRF-induced ACTH secretion (P < .05) was counteracted by pretreatment with nifedipine. Pretreatment with nifedipine further inhibited (P < .01) the GHRH-induced increase in plasma concentrations of GH (P < .05), which, in keeping with previous data, had already been reduced by IV endothelin-1 alone (P < .05). Thus, both endothelin-1 and nifedipine influence pituitary hormone secretion in healthy man. However, nifedipine does not ubiquitously counteract the effects of endothelin-1 since it enhances some of its actions on the pituitary and diminishes others. Endothelin-1 may therefore influence pituitary function by mechanisms other than activation of calcium channels alone.
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