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

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.