Glomerular atrial natriuretic factor receptors during rehydration: plasma NH2- and COOH-terminal levels

Atrial natriuretic factor (ANF) concentration in atria and plasma was investigated in relation to the density and affinity of renal glomerular ANF receptors during water deprivation and rehydration in the rat. Immunoreactive (IR) ANF-(99-126) was lower during water deprivation (4.2 +/- 0.5 fmol/ml) than in normally hydrated animals (10 +/- 1.5 fmol/ml); NH2-terminal IR ANF-(1-98) was also lower in water-deprived rats (75 +/- 2.4 fmol/ml) than in the controls (708 +/- 105 fmol/ml). These decreased plasma COOH- and NH2-terminal ANF concentrations were accompanied by significantly higher hematocrit, serum osmolality, and Na+ values. The renal glomerular ANF receptor population was greater in water-deprived animals than a control animals. After rehydration, IR ANF was elevated within 1 h and reached control values after 6 h. Hematocrit, serum osmolality, and Na+ did not normalize until 48, 6, and 24 h, respectively. The renal glomerular ANF receptor population, which was markedly higher in water-deprived rats, gradually declined after rehydration, so that no difference was observed with the control group 24 h later.