We examined the effects of 60 min alpha-hANP infusion (24 ng/min/kg) on glomerular filtration rate (GFR), renal blood flow (RBF), cardiac index (CI) and blood pressure (BP) in 8 patients with chronic renal failure (CRF) with GFR ranging from 18 to 80 ml/min/1.73 m2 and in 8 control (C) subjects with normal renal function. Basal plasma levels of ANP and cGMP were elevated in CRF (ANP: 60.6 +/- 9.1 vs 13.6 +/- 1.9 pmol/l, p less than 0.05; cGMP: 14.3 +/- 2.9 vs 6.6 +/- 1.1 pmol/ml, p less than 0.05). During ANP infusion, peak levels of cGMP were higher in CRF than in C (27.5 +/- 3.2 vs. 17.3 +/- 1.3 pmol/ml, p less than 0.05). During ANP infusion, GFR increased in CRF by 70.7 +/- 4.2% from 34.5 +/- 6.8 to 57.4 +/- 9.9 ml/min/1.73 m2 (p less than 0.001) as compared to 16.2 +/- 1.4% in C (p less than 0.001 vs CRF). RBF increased in CRF by 43.6 +/- 6.4% and in C by 3.1 +/- 1.2% (p less than 0.01). Basal urinary sodium excretion (UNaV) was slightly lower in CRF than in C but rose to the same level in both groups during ANP infusion. In CRF, as opposed to C, UNaV remained elevated above baseline after the end of the infusion. The effect of ANP on fractional sodium excretion (FENa), however, was more pronounced in C.(ABSTRACT TRUNCATED AT 250 WORDS)