Differential effects of rat pregnancy on uterine and lung atrial
natriuretic factor receptors.
Vaillancourt, Patrice, Saeed Omer, Xing-Fei Deng, Shree Mulay, and
Daya R. Varma.
Departments of Physiology and Medicine and the Department of
Pharmacology and Therapeutics, McGill University, Montreal, Quebec,
Canada H3G 1Y6
APStracts 4:0214E, 1997.
We investigated if the refractoriness to the tocolytic effects of
atrial natriuretic factor (ANF) during rat pregnancy is due to a
downregulation of one or both guanylyl cyclase (GC)-coupled GC-A and
GC-B ANF receptors; lungs were used as controls. Uteri and lungs of
virgin, pregnant (days 7, 16 and 21) and day 2 postpartum rats
expressed mRNAs for GC-A and GC-B as well as GC-uncoupled ANF-C
receptors. GC-B receptor protein was more abundant than GC-A in
uteri; the reverse was the case in lungs. Pregnancy decreased uterine
mRNAs and proteins for GC-A and GC-B receptors as well as the effects
of ANF and C-type natriuretic peptide (CNP) on uterine GC activity;
lung ANF receptors and effects of ANF and CNP on lung GC activity
were not modulated by pregnancy. It is concluded that pregnancy
-induces organ specific modulation of ANF receptors and a
downregulation of ANF-GC receptors would minimize interference with
uterine motility during pregnancy.
Received 31 July 1997; accepted in final form 24 September 1997.
APS Manuscript Number E359-7.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1997 The American Physiological Society.
Published in APStracts on 7 October 1997