Fig. 4.

Urinary urea nitrogen excretion in response to dietary protein restriction. A: in PT-GS-KO mice, there were no significant time-dependent changes during 20% protein diet. In response to dietary protein restriction, urinary urea nitrogen excretion decreased rapidly and was significantly less in PT-GS-KO mice fed 6% protein diet than those fed 20% protein (P < 0.02). *P < 0.05 vs. 20% protein diet on an individual day; n = 6 in each group. B: comparison of the ability of Control and PT-GS-KO mice to alter urinary urea nitrogen excretion in response to dietary protein restriction. Urea nitrogen excretion did not differ significantly in the two genotypes, either under basal conditions or in response to a 6% protein diet; n = 6 in each genotype.