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.
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.
Vierhapper
H
H
University Clinic for Internal Medicine III, Division of Clinical Endocrinology and Metabolism, Wien, Austria.
D000324:Adrenocorticotropic Hormone / Q000097:blood; D000328:Adult; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D016232:Endothelins / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D005640:Follicle Stimulating Hormone / Q000097:blood; D013006:Growth Hormone / Q000097:blood; D006801:Humans; D007986:Luteinizing Hormone / Q000097:blood; D008297:Male; D009543:Nifedipine / Q000494:pharmacology*; D010908:Pituitary Hormones, Anterior / Q000097:blood*; D011388:Prolactin / Q000097:blood; D012016:Reference Values; D013972:Thyrotropin / Q000097:blood
D002121:Calcium Channel Blockers; D016232:Endothelins; D010908:Pituitary Hormones, Anterior; D000324:Adrenocorticotropic Hormone; D011388:Prolactin; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone; D013972:Thyrotropin; D013006:Growth Hormone; D009543:Nifedipine