AJP - Endocrinology and Metabolism, Vol 269, Issue 3 E598-E604, Copyright © 1995 by American Physiological Society

ARTICLES

Inhibition of ACTH secretion blocks hypoxia-induced increase of adrenal cortical blood flow in fetal sheep

A. M. Carter, J. Homan, M. Fraser, B. S. Richardson and J. R. Challis
Department of Obstetrics and Gynecology, Lawson Research Institute, University of Western Ontario, London, Canada.

To examine the role of endogenous adrenocorticotropic hormone (ACTH) in adrenal blood flow responses to hypoxia, we studied unanesthetized ovine fetuses during an intravenous infusion of cortisol or vehicle. Fetal hypoxia was induced after 5 h of cortisol or vehicle infusion. Control fetuses were not made hypoxic. Blood flows were determined before and at three time points during the infusions. At 2 and 6 h of hypoxia, in vehicle-infused fetuses, fetal plasma concentrations of immunoreactive ACTH (irACTH) had risen from 9 +/- 3 (SE) pg/ml to 68 +/- 25 and 127 +/- 37 pg/ml, respectively. No significant change in fetal plasma irACTH occurred in the other groups. Adrenal cortical blood flow rose three- to fourfold during hypoxia in vehicle-infused fetuses but did not change from prehypoxia levels in cortisol-infused fetuses (P < 0.005). Medullary flow rose with hypoxemia, and this was not affected by concurrent cortisol infusion. Adrenal blood flows did not change in the control groups. Thus prior infusion of cortisol suppressed the rise in fetal plasma ACTH during hypoxia and selectively blocked the increase in adrenal cortical blood flow.

This article has been cited by other articles:

				L. F. Buchwalder, M. Lin, T. J. McDonald, and P. W. Nathanielsz Fetal sheep adrenal blood flow responses to hypoxemia after splanchnicotomy using fluorescent microspheres J Appl Physiol, January 1, 1998; 84(1): 82 - 89. [Abstract] [Full Text] [PDF]