The effect of dietary protein level on plasma urea and transaminase activities in uremic rats.

Abstract

The effect of dietary protein level on plasma urea nitrogen, glutamicoxalacetic (GOT) and glutamic-pyruvic (GPT) transaminase activities was studied in uremic rats. Uremic, sham-operated and unoperated female rats weighing approximately 150-250 g were matched according to body weight and assigned at random to diets containing 5% protein (casein) and 230/0 protein (Purina Lab Chow). At both levels of protein intake uremic rats gained less weight than their controls, and the sham-operated rats. The urea concentration was higher in both groups of uremic rats, being significantly higher in the group fed 23% protein, while both GOT and GPT enzyme activities were dramatically lower in comparison with the sham-operated and the unoperated control rats. However, the levels of the transaminase enzymes were lower in the uremic rats fed 23% protein, in which the plasma urea concentration was higher than in the uremic rats fed protein. The higher transaminase activities, along with lower urea levels in the 5% protein_than the 23% protein-fed rats indicates that a reduced protein intake may be of benefit in reducing the severity of the toxic symptoms associated with renal insufficiency. These data indicate that time, diet and uremia induction have direct relationships with body weight gains and urea plasma concentrations. Inversely proportional relationships were observed for GOT and GPTactivities with respect to both diet and time. The low activities of both GOT and GPT found in the uremic rats may be due to an inhibition by urea or by some other substances present in the uremic serum. The reduction of the transaminase enzymes to near zero activities in the chronically uremic rats suggests a possible importance of these enzymes in the clinical diagnosis of renal disorders in man.