Role of the adrenal glands in the maturation of lung liquid
secretory mechanisms in fetal sheep.
Wallace, M. J., S. B. Hooper, and R. Harding.
Department of Physiology, Monash University, Clayton, Victoria,
3168, Australia
APStracts 2:0205R, 1995.
Our aim was to determine the role of the fetal adrenal glands in the
gestational age-related increase in the ability of epinephrine to
induce the reabsorption of lung liquid. Fetal lung liquid volumes and
secretion rates were measured in 5 chronically catheterised control
and 6 bilaterally adrenalectomised (ADX) fetal sheep at 5 day
intervals from 120-144 days of gestation (term 146 days). The ability
of epinephrine to induce the reabsorption of fetal lung liquid was
then determined on day 144. Fetal adrenalectomy prevented the pre
-parturient increase in fetal plasma cortisol and triiodothyronine
(T3) concentrations and significantly reduced the gestational age
-related increase in fetal lung liquid volumes and secretion rates.
Close to term (144 days), epinephrine infusions caused a
significantly greater rate of lung liquid reabsorption in control
(32.2 +/- 4.8 ml/h) compared to ADX (3.7 +/- 0.7 ml/h) fetuses. We
conclude that the presence of the fetal adrenal glands are necessary
for the age-related increase in (1) the lung liquid secretion rate
and (2) the ability of the fetal lung to reabsorb liquid late in
gestation. It is likely that cortisol is the active adrenal hormone
involved, supporting the theory that cortisol plays a crucial role in
the clearance of lung liquid at birth.
Received 14 February 1995; accepted in final form 18 July 1995.
APS Manuscript Number R112-5.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 30 July 1995.