EFFECTS OF ATRIAL-NATRIURETIC-PEPTIDE ON SYSTEMIC AND RENAL HEMODYNAMICS AND RENAL EXCRETORY FUNCTION IN PATIENTS WITH CHRONIC-RENAL-FAILURE

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 < 0.05; cGMP: 14.3 +/- 2.9 vs 6.6 +/- 1.1 pmol/ml, p < 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 < 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 < 0.001) as compared to 16.2 +/- 1.4% in C (p < 0.001 vs CRF). RBF increased in CRF by 43.6 +/- 6.4% and in C by 3.1 +/- 1.2% (p < 0.01). Basal urinary sodium excretion (U(Na)V) 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, U(Na)V remained elevated above baseline after the end of the infusion. The effect of ANP on fractional sodium excretion (FE(Na)), however, was more pronounced in C. Basal FE(Na) was higher in CRF (12.8 +/- 2.5% vs 2.4 +/- 1.5% in C, p < 0.001), FE(Na) remained elevated at 180% over baseline in C sixty minutes after cessation of ANP infusion, while it had returned to baseline in CRF. During ANP infusion, CI increased in CRF after 30 min from 2.91 +/- 0.08 to 3.12 +/- 0.09 l/min/m2 (p < 0.001) and in C from 3.20 +/- 0.11 to 3.39 +/- 0.13 l/min/m2 (p < 0.05). Mean arterial BP was higher in CRF and its decrease was greater than in C (21.1 +/- 2.7% vs 9.1 +/- 1.0%, p < 0.001). In patients with CRF GFR, RPF, and CI remained significantly elevated and BP was still significantly decreased 60 min after ANP infusion. Total peripheral vascular resistance (TPR) was elevated in CRF and declined during ANP infusion in both CRF and C. The decline of TPR was sustained and more pronounced in CRF than in C. Renal vascular resistance (RVR) was high in CRF and dropped by nearly 50% during ANP infusion, whereas only a moderate decline in RVR during ANP application was observed in C. Thus, exogenous ANP had greater and prolonged effects on systemic hemodynamics and renal function in CRF than in C. They may be due to higher levels of ANP following ANP infusion and appear to be mediated by a more sustained formation of the second messenger cGMP.