Nutritional effects of intravenous infusion solutions on normal rats: effects of increased energy level and deletion of acidic amino acids

Nutritional responses of tumor-bearing rats to oral or intravenous feeding

Two experiments were conducted with male rats weighing 170 to 190 grams. In experiment 1, some nutritional parameters were determined in tumor-bearing (TB) (Walker 256 carcinosarcoma) rats fed a 23.6% casein diet for 4 weeks after the tumor inoculation. Cumulative weight gain and food intake were less in TB rats than in nontumor-bearing (NTB) rats. At 3 and 4 weeks after the tumor inoculation, plasma histidine, alanine, and glycine levels were higher in TB rats than in NTB animals. The arginine level was lower in the plasma of TB rats at 4 weeks after the inoculation. The significance of decrease in plasma arginine with regard to tumor growth is discussed. In experiment 2, the effects of total parenteral nutrition (TPN) on TB rats were evaluated as compared with those of 5% glucose (Glc) solution. Body weights of TPN rats were maintained and their nitrogen (N) balances were positive during a 7-day experimental period, while 5% Glc animals showed severe body weight loss and apparent negative N balance. After the end of infusion, the plasma urea level of the TPN group was within normal range, whereas that of 5% Glc group showed a markedly high value. The plasma albumin level was higher in the TPN group. Liver and spleen weights were increased in TPN rats. Absolute tumor weight was somewhat greater in TPN rats than in 5% Glc rats, but the difference in tumor weight:body weight ratios became more slight. These results indicate that TPN was effective for maintaining the nutritional status of TB host without significant acceleration in tumor growth.