Downregulation of renal atrial natriuretic factor receptors and
receptor mrnas during rat pregnancy.
Omer, Saeed, Patrice Vaillancourt, Krishna G. Peri, Daya R. Varma, and
Shree Mulay.
Departments of Physiology and Medicine and Cardiology Division,
Royal Victoria Hospital, McGill University, Montreal, Canada H3A 1A1;
Department of Pharmacology & Therapeutics, McGill University,
Montreal, Canada H3G 1Y6; Research Centre, Ste Justine Hospital,
Montreal, Canada H3T 1C5
APStracts 3:0189F, 1996.
Using renal glomeruli and papillae from virgin, pregnant (15-17 day)
and postpartum (day 2) rats, we investigated if the decrease in the
renal effects of ANF during pregnancy is caused by a downregulation
of ANF receptors. Pregnancy decreased the maximal binding of
[125I]ANF to guanylyl cyclase (GC)-linked ANF-GC receptors in
glomeruli and papillae and increased the binding to clearance
receptors (ANF-C) in glomeruli; ANF-C receptors were not detected in
the papillae. Ribonuclease protection assay detected mRNAs for all
the three receptors in the papillae; pregnancy decreased GC-A and
ANF-C but not GC-B receptor mRNAs. Western blots revealed a decrease
in GC-A receptors in the papillae of pregnant rats; GC-B receptor
protein was barely detectable. Effects of ANF on guanosine 3',5'
-cyclic monophosphate (cGMP) production by the glomeruli and papillae
were decreased during pregnancy and returned to virgin levels during
postpartum. It is concluded that a decrease in the renal effects of
ANF during pregnancy is caused by a downregulation of renal ANF GC-A
receptors and receptor-coupled cGMP production.
Received 3 July 1996; accepted in final form 12 October 1996.
APS Manuscript Number F183-6.
Article publication pending Am. J. Physiol. (Renal Fluid Electrolyte
Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 5 November 1996