Valine metabolism in normal and chronically uremic man.

Valine metabolism was investigated in five normal and three nondialyzed chronically uremic subjects eating 40 +/- SEM 1 and 53 (range 40 to 80) protein diets respectively, in a metabolic research unit. Subjects were injected iv with a tracer dose of L-valine-1-14C while they fasted, and specific activity of plasma valine-14C and expiration of 14CO2 were monitored for two hours. Plasma valine was significantly lower in the uremic patients than in the normal subjects (P less than 0.05). In the uremic patients, specific activity of plasma valine fell less rapidly and remained higher, and expiration of 14CO2 was not different from normal subjects. A two-pool model for valine metabolism was derived which indicated that in uremic patients there was a significant decrease in both valine pools and in the rate of irreversible loss, i.e., valine incorporated into larger molecules, degraded, or excreted. Valine degradation was estimated to be decreased in the uremic patients.