AJP - Endocrinology and Metabolism, Vol 268, Issue 5 E845-E848, Copyright © 1995 by American Physiological Society

ARTICLES

Secretion and clearance of immunoreactive ACTH by fetal lung

T. A. Cudd and C. E. Wood
Department of Physiology, University of Florida College of Medicine, Gainesville 32610-0274, USA.

We have previously reported the presence of immunoreactive adrenocorticotropic hormone (irACTH) in fetal and adult ovine lung and secretion of the irACTH into the pulmonary venous blood during surgical stress. The aim of the present experiments was to determine whether the fetal lung secretes irACTH during less stressful conditions. Seven fetal sheep were chronically prepared with systemic, pulmonary arterial, and pulmonary venous catheters. After recovery from surgery, paired samples were obtained from the pulmonary arterial and venous catheters. In 51 pairs of samples, we quantified the arteriovenous (A-V) difference in plasma irACTH concentration. Pulmonary A-V difference in plasma irACTH was significantly related to the arterial plasma concentration of irACTH but not to fetal blood gases, pH, or gestational age. Regression analysis revealed that, at arterial plasma concentrations of irACTH less than approximately 200 pg/ml, the lung releases irACTH into plasma and that, at higher concentrations, the lung clears irACTH from the plasma. We conclude that the lung independently secretes and clears irACTH into and from plasma.

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				T. M. Jeffray, S. G. Matthews, G. L. Hammond, and J. R. G. Challis Divergent changes in plasma ACTH and pituitary POMC mRNA after cortisol administration to late-gestation ovine fetus Am J Physiol Endocrinol Metab, March 1, 1998; 274(3): E417 - E425. [Abstract] [Full Text] [PDF]