Effects of water deprivation on atrial natriuretic peptide secretion and density of binding sites in adrenal glands and kidneys of maternal and fetalrats in late gestation

The effects of water deprivation for 3 days were studied in pregnant rats a nd their fetuses on day 21 of gestation, Maternal water deprivation induced a significant decrease of the body weight in both maternal and fetal rats. This weight loss was accompanied by significant increases in plasma osmola lity and haematocrit in both maternal and fetal rats. Similarly, dehydratio n significantly decreased plasma atrial natriuretic peptide (ANP) concentra tions and increased plasma aldosterone concentrations in maternal and fetal rats. Water-deprived maternal rats presented a significant increase in tot al ANP receptor density in isolated. renal glomeruli and adrenal zona glome rulosa membranes. This increase was due to a significant increase in ANPc r eceptor density in both renal glomeruli and adrenal zona glomerulosa. The d ensities of total ANP, ANPB and ANPc receptors in fetal kidneys and adrenal glands were not affected by maternal dehydration, These results suggest th at the dehydrated maternal rat is able to up-regulate the number of its ANP receptors in its kidneys and adrenal glands, in response to a decrease in plasma ANP concentrations. In contrast, the fetal rat does not seem to be a ble to regulate its own ANP receptors in response to maternal dehydration, in spite of a decrease in plasma ANP concentrations.