LOW NITROGEN DIETS PRESERVE NUTRITIONAL-STATUS BUT NOT RESIDUAL RENAL-FUNCTION IN RATS WITH SEVERE RENAL-FAILURE

The effects of low nitrogen diets (oral and parenteral) on nutritional status and residual renal function were evaluated in rats with experi mentally induced severe renal failure (partial nephrectomy) and compar ed with the effects of a normal protein diet. Non-uremic rats were use d as controls. Muscle protein synthesis was significantly lower in ure mic rats fed a normal protein diet than in those fed low protein diets . Values for serum insulin-like growth factor 1 (IGF-1) were significa ntly lower than for controls in all uremic groups as were the wet and dry weights of skeletal muscle. The glomerular filtration rate was stu died after 3 wk of nutritional intervention. Serum creatinine concentr ation was lower and creatinine clearance greater in uremic rats given the low nitrogen dietary treatments (both oral and parenteral) compare d with those fed the normal protein diet. However, the glomerular filt ration rate determined with Cr-51-EDTA clearance did not differ betwee n uremic rats with normal and low protein intake. Thus, a low nitrogen diet had positive effects on uremic toxicity and did not compromise n utritional status. The results do not, however, establish a favorable influence on residual renal function and emphasize the need for reliab le methods for studying dietary effects on renal function in uremia.