Downregulation of renal atrial natriuretic factor receptors and receptor mRNAs during rat pregnancy.
Using renal glomeruli and papillae from virgin, pregnant (15- to 17-day), and postpartum (day 2) rats, we investigated whether the decrease in the renal effects of atrial natriuretic factor (ANF) during pregnancy is caused by a downregulation of ANF receptors. Pregnancy decreased the maximal binding of 125I-labeled 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.
Omer
S
S
Department of Physiology, Royal Victoria Hospital, McGill University, Montreal, Quebec, Canada.
Vaillancourt
P
P
Peri
K G
KG
Varma
D R
DR
Mulay
S
S
D000818:Animals; D009320:Atrial Natriuretic Factor; D006152:Cyclic GMP / Q000096:biosynthesis; D015536:Down-Regulation; D005260:Female; D006162:Guanylate Cyclase / Q000378:metabolism; D007668:Kidney / Q000378:metabolism*; D007678:Kidney Glomerulus / Q000378:metabolism; D007679:Kidney Medulla / Q000378:metabolism; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017461:Receptors, Atrial Natriuretic Factor / Q000235:genetics* / Q000378:metabolism*
D012333:RNA, Messenger; C472610:atrial natriuretic peptide, rat; D009320:Atrial Natriuretic Factor; D006162:Guanylate Cyclase; D017461:Receptors, Atrial Natriuretic Factor; D006152:Cyclic GMP