The impact of synthetic atrial natriuretic peptide (sANP) on renal function following cold ischemic injury was studied in a canine autotransplant model. Following a prenephrectomy inulin clearance determination (CIn), the left kidney was excised, flushed with Eurocollins solution, and cold-stored for 24 hours. Immediately following reperfusion and a 10 minute equilibration period, baseline CIn was measured over a 20-minute time interval (Collection Period I). Experimental animals (N = 11) then received 1 mcg/kg sANP by intravenous bolus followed by a continuous infusion at 0.3 mcg/kg/min for 30 minutes. CIn was measured throughout the infusion (Collection Period II). Normal saline was substituted for sANP in control animals (N = 11). CIn was also measured 24 hours following reimplantation in seven control and seven sANP-treated animals. Autograft inulin clearance increased from 0.32 +/- 0.11 ml/min during Period I to 2.5 +/- 0.6 ml/min during sANP infusion (P less than 0.01). This increase in CIn associated with ANP infusion was accompanied by increases in urine flow rate (V) (0.15 +/- 0.05 ml/min to 0.98 +/- 0.21 ml/min, P less than 0.01) and renal blood flow (RBF) measured by electromagnetic flow probe (85 +/- 17 ml/min to 171 +/- 13 ml/min, P less than 0.05). No significant changes in CIn, V, or RBF occurred in control animals between periods I and II. Although systemic blood pressure declined during sANP infusion, it did not decrease to an extent that compromised peripheral perfusion. CIn determined 24 hours after autograft reimplantation in the ANP-treated animals approximated or exceeded values determined during ANP infusion (Period II).(ABSTRACT TRUNCATED AT 250 WORDS)