Rat renal, aortic and pulmonary endothelin-I receptors: effects of changes in sodium and water intake.

1. In the present study we investigated, first, the effects of high Na+ intake and, second, the effects of water deprivation on plasma endothelin-1 concentration and urinary endothelin-1 excretion and on endothelin receptors in membranes of renal glomeruli and papillae and of aortic smooth muscle and lung tissue from 32 female Sprague-Dawley rats. 2. After 5 weeks of high Na+ intake (n = 8) urinary Na+ excretion was 10.5 +/- 1.3 compared with 1.6 +/- 0.2 mmol/24 h in controls. Body weight, plasma osmolarity, plasma endothelin-1 concentration (23 +/- 6 versus 28 +/- 3 fmol/ml) and urinary endothelin-1 excretion (6.1 +/- 1.3 versus 4.7 +/- 0.3 pmol/24 h) remained unchanged. 3. The characteristics of endothelin-1 receptors in glomeruli, papillae, aortic smooth muscle and lung tissue from salt-loaded rats were not different from those of controls. 4. After 48 h water deprivation (n = 8) body weight had decreased, whereas packed cell volume and plasma and urine osmolarities had increased compared with controls (n = 8) (P < 0.05). Plasma endothelin-1 concentration (40 +/- 6 versus 21 +/- 2 fmol/ml) was higher (P < 0.01) and urinary endothelin-1 excretion (1.0 +/- 0.2 versus 2.8 +/- 0.3 pmol/24 h) was lower than in controls (P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)