title: Osmoregulation of systemic vasopressin release during long-term glucocorticoid excess: a study in dogs with hyperadrenocorticism.
abstract: In 9 dogs with pituitary-dependent hyperadrenocorticism and in 6 dogs with hyperfunctioning adrenocortical tumours, the osmoregulation of arginine vasopressin (AVP) release was investigated by iv infusion of 20% NaCl for 2 h at a rate of 0.03 ml per kg body weight. The responses were analysed in terms of sensitivity and threshold of the osmoregulation of AVP secretion. The sensitivity was normal in 6 dogs and lowered in 9. In 4 of the latter dogs there was complete absence of a response to hypertonicity. The osmotic threshold of AVP release was raised in 9 dogs and normal in 2 dogs, whereas in the four dogs without any response the term threshold was not applicable. The results were not different for dogs with pituitary-dependent hyperadrenocorticism and dogs with hyperfunctioning adrenocortical tumour. It is concluded that corticosteroid excess per se induces a marked impairment of the osmoregulation of AVP secretion. The loss of reactivity of the osmoreceptor system may contribute to the corticosteroid-induced polyuria, which is also the result of resistance to AVP in the kidney.
authors.affiliation: Department of Clinical Sciences of Companion Animals, Faculty of Veterinary Medicine, University of Utrecht, The Netherlands.
authors.forename: W J
authors.initials: WJ
authors.lastname: Biewenga
authors.forename: A
authors.initials: A
authors.lastname: Rijnberk
authors.forename: J A
authors.initials: JA
authors.lastname: Mol
mesh_terms: D000302:Adrenal Cortex / Q000378:metabolism* / Q000503:physiopathology; D000306:Adrenal Cortex Neoplasms / Q000097:blood / Q000503:physiopathology; D000308:Adrenocortical Hyperfunction / Q000378:metabolism / Q000503:physiopathology*; D000818:Animals; D001127:Arginine Vasopressin / Q000378:metabolism*; D004285:Dogs; D005260:Female; D005938:Glucocorticoids / Q000502:physiology*; D007262:Infusions, Intravenous; D008297:Male; D012462:Saline Solution, Hypertonic / Q000494:pharmacology*; D014882:Water-Electrolyte Balance / Q000187:drug effects / Q000502:physiology*
chemical_list: D005938:Glucocorticoids; D012462:Saline Solution, Hypertonic; D001127:Arginine Vasopressin