Nitrogen retention, muscle creatine and orotic acid excretion in traumatized rats fed arginine and glycine enriched diets.

Male, Sprague-Dawley rats were subjected to the trauma of laparotomy under sodium pentothal anesthesia. Apparent N retention (N intake - Urinary N) was studied when these rats were fed a 25% casein diet either unsupplemented or enriched with arginine plus glycine or with ornithine plus glycine. These amino acids occur in particularly high concentrations in skin and connective tissue and might, therefore, be required in greater amounts for tissue repair. In one experiment muscle creatine content and orotic acid excretion in the urine were determined. We found that laparotomy carried out under sodium pentothal anesthesia was a highly reproducible form of trauma which resulted in a significant decrease in apparent N retention. Supplementing a 25% casein based diet with arginine and glycine significantly improved apparent N retention both in untraumatized as well as in traumatized rats. Ornithine was less effective than arginine in improving apparent N retention. Urinary orotic acid excretion was significantly increased in rats fed the unsupplemented casein diet, regardless of the imposition of trauma. Muscle creatine content was significantly increased by the supplementation of the diet with arginine plus glycine. The beneficial effect of arginine-plus-glycine enrichment in traumatized rats does not appear to be due to an arginine deficit needed for the detoxification of ammonia from excess amino acids but may be related to creatine synthesis and turnover.