[Changes in the distribution of urea in body fluids during growth]

Urea concentration in plasma, muscle, and liver fluids of Wistar rats at the age of 3, 6, and 12 weeks was determined. In rats at the age of 3 weeks urea was cumulated in liver and muscle tissue fluids, in older rats (6 and 12 weeks) in plasma fluid. According to the stated urea distribution in individual age categories, a higher urea transport from tissues to blood is considered to be in rats at the age of 6 and 12 weeks. The urea transport proved to be one of the mechanisms of facilitating better utilization of endogenous urea nitrogen in bio-synthetic processes of the nitrogen metabolism in ruminants as well as in monogastric animals.