Sepsis Modifies the Contribution of Different Organs to Whole-Body Protein Synthesis in Rats

Abstract

1. Protein synthesis rate was measured in the liver, muscle, intestine and whole body of septic rats and pair-fed controls by administration of a large dose of l-[U14C]valine. Sepsis was induced by intravenous injection of live bacteria, and protein synthesis measurements were carried out 48 h later. 2. Septic rats exhibited a reduction in food intake to between 10 and 50% of the normal level on the 2 days after infection. Animals lost body weight and the relative organ weight was increased in liver, unchanged in intestine and decreased in skeletal muscle. 3. The fractional protein synthesis rate of the whole body excluding liver was increased by 19% in septic rats in comparison with pair-fed controls, but the absolute protein synthesis rate was similar in the two groups because of the low protein content of the infected group. 4. The fractional protein synthesis was increased in whole intestine and liver but was decreased in skeletal muscle. In muscle and liver, the difference between infected and pair-fed animals was more pronounced for the absolute than for the fractional protein synthesis rate. In intestine, the fractional protein synthesis rate was similarly increased in whole intestine and the muscular layer of ileum. This suggests different regulation of protein synthesis in skeletal and smooth muscles. 5. The present investigation shows a complete redistribution of protein synthesis in sepsis. Liver represents about a third of the whole-body protein synthesis instead of 15% and becomes predominant over synthesis of muscle.