Endocrine responses of fetal lambs to hemorrhage after alpha 1-adrenergic receptor blockade.
To determine the importance of alpha 1-adrenergic receptors in the endocrine responses of fetal lambs to hemorrhage, eight chronically instrumented fetal lambs were bled of 20% of their measured blood volume after pretreatment with prazosin (24.8 +/- 2.1 days' gestation) or inert vehicle (124.2 +/- 2.2 days' gestation) according to a randomized, crossover protocol. Cortisol levels increased threefold with prazosin injection and remained elevated after hemorrhage but did not change with hemorrhage after vehicle infusion. Plasma renin activity was unaffected by the injection of prazosin but increased in both groups after hemorrhage. Vasopressin levels were unchanged in the control group throughout the experiment but increased tenfold with hemorrhage after pretreatment with prazosin. alpha 1-Adrenergic receptor blockade removes adrenergic inhibition of cortisol secretion and changes the hypotensive threshold for the secretion of vasopressin.
D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology*; D000818:Animals; D004702:Endocrine Glands / Q000503:physiopathology*; D006439:Hemodynamics / Q000187:drug effects; D006470:Hemorrhage / Q000097:blood / Q000503:physiopathology*; D006854:Hydrocortisone / Q000097:blood; D011224:Prazosin / Q000494:pharmacology; D012083:Renin / Q000097:blood; D012756:Sheep / Q000196:embryology; D014667:Vasopressins / Q000097:blood
D000317:Adrenergic alpha-Antagonists; D014667:Vasopressins; D012083:Renin; D006854:Hydrocortisone; D011224:Prazosin