title: Responses of immunoreactive ACTH and bioactive ACTH to large hemorrhage and resuscitation in conscious dogs.
abstract: We studied the effect of fluid resuscitation on immunoreactive adrenocorticotropic hormone (irACTH) and bioactive ACTH (bioACTH) after hemorrhage in conscious dogs. Animals (n = 7) were bled 30% (approximately 25 ml/kg) over 3 min and 30 min later were either resuscitated [43.3 ml/kg 0.9% NaCl (1.8 times hemorrhage volume) over 10 min] or not. Blood was reinfused after 210 min. Animals had both treatments (> 4 days apart). irACTH, bioACTH, cortisol, angiotensin II, and aldosterone increased rapidly after hemorrhage. Resuscitation increased blood volume and cardiac output to resting values, but arterial hypotension persisted. bioACTH and irACTH decreased 40-90 min after hemorrhage in both groups, but each decreased more rapidly after resuscitation. The elimination half-life of bioACTH was shorter than that of irACTH, but neither was affected by resuscitation. The ratio of bioACTH to irACTH followed the same pattern with or without resuscitation. Angiotensin II and aldosterone remained increased without resuscitation but decreased promptly after resuscitation. In conclusion, 1) saline infusion at 1.8 x hemorrhage volume provides effective cardiovascular resuscitation, with resolution of hormonal responses to hemorrhage; 2) although ACTH responses resolved with or without resuscitation, resuscitation produced more rapid resolution without changing the parameters of ACTH elimination; 3) the dynamics of the resolution of the ACTH response to hemorrhage are similar whether induced by stimulus removal or feedback inhibition.
authors.affiliation: Department of Surgery, School of Medicine, University of Maryland at Baltimore 21201, USA.
authors.forename: M P
authors.initials: MP
authors.lastname: Lilly
authors.forename: G J
authors.initials: GJ
authors.lastname: Gala
authors.forename: B E
authors.initials: BE
authors.lastname: Sutherland
authors.forename: D S
authors.initials: DS
authors.lastname: Gann
mesh_terms: D000324:Adrenocorticotropic Hormone / Q000097:blood*; D000450:Aldosterone / Q000097:blood; D000804:Angiotensin II / Q000097:blood; D000818:Animals; D001681:Biological Assay; D004285:Dogs; D005260:Female; D006439:Hemodynamics; D006470:Hemorrhage / Q000097:blood* / Q000503:physiopathology; D006854:Hydrocortisone / Q000097:blood; D008297:Male; D011863:Radioimmunoassay; D012151:Resuscitation
chemical_list: D000804:Angiotensin II; D000450:Aldosterone; D000324:Adrenocorticotropic Hormone; D006854:Hydrocortisone