Renal function in rats with acute medullary injury

Acute, reversible renal failure affecting primarily medullary structures, was produced by feeding rats a diet containing 5% oxonic acid and 2.5% uric acid for 7 days. Inulin clearance and selected tubular transport processes were studied and compared to controls. At the time of maximal renal injury, inulin clearance was reduced to 40% of control values, in association with a 60% reduction in urine concentrating ability, a 50% reduction in potassium excretion and a 56% reduction in ammonium excretion. During a 7-day recovery period, inulin clearance increased to 70% of control and potassium excretion returned to normal while the other tubular transport functions remained impaired. Thus, in acute renal failure, tubular functional impairments may recover at different rates.