Effect of parenteral nutrition on protein turnover in endotoxaemic rats

1. Intravenous infusion of endotoxin into rats over 18 h caused a reduction in food intake to 20% of normal levels, weight loss, hypoalbuminaemia and a fall in rates of protein synthesis in vivo in heart and skeletal muscle. 2. Measurements of protein turnover in vitro in skeletal muscle of endotoxaemic animals, showed a 50% fall in protein synthesis rates and a 200% increase in rates of protein degradation. 3. Total parenteral nutrition was only partially able to reverse endotoxin-induced weight loss. Total parenteral nutrition did not reverse endotoxin-induced catabolism in cardiac or skeletal muscle, but was able to reverse the catabolism of protein in skeletal muscle produced by starvation. 4. Endotoxin treatment elevated rates of protein synthesis in vivo in liver. The combination of parenteral nutrition and endotoxaemia further increased the rate of protein synthesis in the liver. Parenteral nutrition did not influence endotoxin-induced hypoalbuminaemia.