Comparison of pH Modified Total Parenteral Nutrition Solution in Affecting Metabolism and Acid-base Homeostasis in Parenterally Fed Rats

Abstract

Patients who received long-term total parenteral nutrition (TPN) solution are possibly affected by metabolic acidosis due to the acid load from the TPN solution. The objective of this study was to determine if a pH modified TPN solution would alter the metabolism and acid-base homeostasis in vivo. Male Wistar rats (～250 g), subjected to jugular vein cannulation (day 0), were infused with hydrochloric acid-acidified (pH 4. 5), sodium hydroxide-alkalized (pH 6, 5), or conventional (pH 5. 5) TPN solution for 12 days. A normal parenterally fed rat model (TPN model) and a dexamethasone-induced catabolic rat model (DEX model) were tested. Our results showed that alkalized but not acidified TPN solution significantly increased weight loss, relative weights of heart, liver, and spleen (g/kg body weight), and the circulating members of white blood cells in the TPN model. In addition, nitrogen retention, red blood cells, hemoglobin, bicarbonate, albumin, and insulin-like growth factor-I levels were significantly decreased in rats with alkalized TPN solution compared to rats with traditional TPN solution. In contrast, there was no significant difference in growth response among the groups in the DEX model. However, DEX-treated animals infused with acidified TPN solution showed significantly greater serum level of triglyceride and lower relative lung weight than those infused with traditional TPN solution. Our results suggest that sodium hydroxide-alkalized (pH 6. 5) TPN solution may induce catabolism and acid-base imbalance in normal rats. However, hydrochloric acid-acidified (pH 4. 5) TPN solution may induce metabolic disorders in dexamethasone-treated rats.