AJP - Regulatory, Integrative and Comparative Physiology, Vol 249, Issue 2 281-R284, Copyright © 1985 by American Physiological Society

ARTICLES

Control of ACTH and vasopressin in neurohypophysectomized conscious dogs

H. Raff, D. Merrill, M. Skelton and A. W. Cowley Jr

Adrenocorticotropin (ACTH), cortisol, and vasopressin responses to clamped decreases in blood pressure (MAP) and to ovine corticotropin-releasing factor (CRF) infusion (20 ng X kg-1 X min-1) in intact and neurohypophysectomized (NHX) conscious dogs were examined. Mean arterial blood pressure was decreased 28 mmHg by a controlled infusion of sodium nitroprusside. Hypotension induced large increases in ACTH (peak 164 +/- 25 pg/ml), cortisol (peak 12.5 +/- 2.5 micrograms/dl), and vasopressin (peak 221 +/- 64 pg/ml) in intact (n = 7) dogs. NHX (n = 7) significantly attenuated these responses to hypotension. CRF infusion induced increases in ACTH similar in intact (n = 4) and NHX (n = 4) dogs. However, cortisol responses were significantly attenuated by NHX. Interestingly, CRF infusion induced small but significant increases in vasopressin from 3.0 +/- 1.1 to 8.1 +/- 2.0 pg/ml. We conclude that NHX attenuates ACTH and vasopressin responses to hypotension and cortisol responses to CRF-induced increases in ACTH. CRF seems to stimulate vasopressin release.