Dehydration increases the density of C receptors for ANF on rat glomerular membranes

Abstract

The present study determined the presence of two types of binding sites for atrial natriuretic factor (ANF), the B and C receptor, on rat glomerular membranes. The effect of short-term salt loading and dehydration on these two receptor populations was investigated consecutively. Salt-loaded rats did not show significant changes in plasma ANF concentrations or in the number of ANF binding sites. Water-deprived rats presented significantly lower plasma ANF concentrations (22.0 +/- 1.9 vs. 34.4 +/- 3.8 fmol/ml, P less than 0.01) and an increase in total receptor density (1,860 +/- 398 vs. 987 +/- 143 fmol/mg protein) as compared with the control group. Differentiation of both receptor populations showed that it was the C receptors that accounted for this increase (1,772 +/- 369 vs. 901 +/- 151 fmol/mg protein, P less than 0.05), whereas B-receptor density was unchanged (89 +/- 31 vs. 87 +/- 44 fmol/mg protein). These data suggest that C receptors for ANF are affected by changes of body fluid volume.

Atrial natriuretic peptide and aldosterone secretions, and atrial natriuretic peptide-binding sites in kidneys and adrenal glands of pregnant and fetal rats in late gestation in response to a high-salt diet

“…Unfortunately, in our study, the plasma ANP levels in the fetal and pregnant rats were not significantly modified by a high-salt diet, suggesting that the amount of salt intake with saline solution does not interfere with ANP secretion. This result is in agreement with those of several investigations which showed that a high-salt diet did not modify the release of ANP in the adult rat (15,16,22,23) the pregnant rat (5,35). Previous studies have shown that the blood volume expansion is the physiological stimulus of ANP secretion by increasing atrial distension in the adult rat (36,37) and the fetal rat (38).…”

“…The density of ANPb receptors was assessed with rANP in the presence of an excess of cANP (4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23) (0.1 mmol/l; Peninsula), a truncated ANP peptide which binds selectively to ANPc receptors. The density of ANPc receptors was obtained by subtracting the number of ANPb receptors from the total receptor population.…”

“…Indeed, in a recent study, we have shown that water deprivation significantly increased the total number of ANP receptors in renal glomeruli and adrenal zona glomerulosa membranes of the pregnant rat (49). The use of cANP (4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23) allowed us to demonstrate that the population of ANPc receptors increases in the renal glomeruli and adrenal zona glomerulosa of the pregnant rat, whereas the ANPb receptor density remains unchanged (49). In contrast, the absence of upregulation of ANP receptors in fetal kidneys and adrenal glands from dehydrated mothers could be associated with the immaturity of those organs (49).…”

“…The results of these studies were often controversial. Indeed, some investigators have described an increase of plasma ANP concentration after salt-loading intake (14,18,19), while others have demonstrated a decrease of plasma concentrations after salt-overloading (20,21) and others have shown that plasma ANP concentrations were not significantly altered by high-sodium intake (15,16,22,23). These discrepancies can be explained by the differences in the protocols used in these experiments.…”

Effects of dehydration on endocrine regulation of the electrolyte and fluid balance and atrial natriuretic peptide-binding sites in perinatally malnourished adult male rats

“…Thus, many studies in rats have shown that dehydration enhances plasma VP levels (34,35) as well as hypothalamic VP gene expression (34,36). Dehydration also causes a rise in plasma aldosterone levels (37), a fall in plasma ANP concentrations (38,39) and an increase in ANP-C receptor density in kidneys (38). It is not known if perinatal maternal malnutrition alters these homeostatic responses to dehydration.…”