1. The influence of an acute-phase reaction on the ability of protein synthesis rates in liver and three different muscles (gastrocnemius, soleus and heart) to respond to a short intravenous infusion of nutrients (glucose plus amino acids) was investigated during experimental inflammation induced by injection of human recombinant interleukin-1β or turpentine in young male rats.
2. Interleukin-1β induced a consistent increase of 3°C in body temperature between 3 and 5 h after injection, whereas turpentine induced a delayed fever, peaking by 13 h.
3. Interleukin-1β and turpentine stimulated fractional rates of protein synthesis in liver. The synthesis rate was inhibited by interleukin-1β in gastrocnemius and soleus muscle, but an elevation was seen in heart muscle. In this study there was no significant response of muscle to turpentine injection.
4. Two hours of parenteral nutrition increased fractional synthesis rates in all tissues when compared with Ringer's lactate. Somewhat larger responses to feeding were observed as a result of either interleukin-1β or turpentine injection in all tissues, but these improvements were not significant.
5. We conclude that the response of protein synthesis rates in liver and skeletal muscle to parenteral nutrition is not inhibited, and may be somewhat enhanced, during acute inflammatory conditions in the growing rat.