The effect of the atrial natriuretic factor (ANF) on early norepinephrine-induced acute renal failure (ARF) was investigated. In anaesthetized female Sprague-Dawley rats, weighing 247 +/- 36 g, ARF of the left kidneys was induced by 40-min intrarenal arterial infusion of norepinephrine (NE; 0.75 micrograms/kg body weight). In each case the right kidney served as a control organ. Inulin clearance was used as an estimate of glomerular filtration rate (GFR). Urine volume (V), GFR and fractional excretion rates of sodium, potassium and chloride were studies in both kidneys. Immediately after NE-induced ARF one group received ANF (alpha-hANaP) and the other groups 5% glucose or isotonic saline; all infusions were administered intrarenally. In the experimental kidney NE-infusion induced anuria. ANF infusion was able to induce complete reversal of the NE effect, and GFR and diuresis improved markedly in the experimental kidney. In addition, a tremendous rise in fractional excretion rates of sodium and potassium after administration of ANF was observed. In the control kidney an additional increase of GFR and diuresis was seen. Following 5% glucose or isotonic sodium chloride infusion, no profound effects were obtained in both kidneys. The results of the present study demonstrate that ANF provides beneficial effects on the functional damage of NE-induced ARF. We conclude that the NE-antagonistic effect of ANF and the consecutive amelioration of GFR may play an important role in the recovery of impaired renal function.