Renal Tubular Excretion of Urea in Kangaroo Rats

Abstract

The renal function in the desert rodents, Heteromyidae, was studied since these animals have an unusually high osmotic ceiling in their urine. Tubular excretion of urea was indicated by urea/inulin clearance ratios higher than unity when the inulin U/P ratio was below 50. Urea/ inulin clearance ratios were higher in animals maintained on a high protein diet (soy beans, about 40% protein) than in those on a low protein diet (barley, about 8% protein). The urea/ inulin clearance ratios were depressed during mannitol diuresis.