Growth of rats with severe renal insufficiency fed a formula designed to minimize urinary solutes

Experiments were designed to test the hypothesis that growth depression and azotemia in chronic renal failure can be minimized by providing a nutritional formula that is adequate is essential nutrients but minimizes urinary excretion of all solutes. Unrestrained rats were fed exclusively by continuous intragastric infusion with a mixture containing sucrose, essential amino acids, N-free analogues thereof, minerals, corn oil, and vitamins, designed to minimize urinary solute excretion while permitting growth. After 5 days, renal excretory function was reduced to 1/10 by reinfusing 90% of each day's urinary output intragastrically for the next 3 wk. Weight gain (3.6 +/- 0.1 g/day), linear growth and carcass N accretion were the same as in nonreinfused rats receiving substantially the same formula by intragastric catheter. Except for sight acidosis (CO2 18.5 mM) accumulation of electrolytes did not occur. Average final serum urea N was only 42.5 +/- 7.1 mg/dl. The results are considered as supporting the hypothesis.