PROTEIN-METABOLISM IN SPECIFIC TISSUES OF ENDOTOXIN-TREATED RATS - EFFECT OF NUTRITIONAL-STATUS

Rats received an injection of [C-14]leucine and were then divided into four groups. Groups I and II consisted of ad libitum fed rats were ad ministered saline or endotoxin of Salmonella enteritidis eight and twe nty-two h after the [C-14]leucine treatment. Animals of Group III (sal ine) and Group IV (endotoxin) fasted after [C-14]leucine injection. Tw enty three hours after [C-14]leucine treatment rats were injected with [H-3]leucine and sacrificed 20 min afterwards. Endotoxin administrati on decreased body weight in fed rats only. After endotoxin treatment, higher [H-3]leucine specific activity in the blood plasma, decreased l eucine incorporation into proteins and lowered plasma amino acid level s were observed. [C-14]leucine radioactivity was significantly higher in the spleen and lower in skeletal muscles of endotoxin-treated rats. All changes were less expressed in fasted than in ad libitum fed anim als. Our results indicate that endotoxin treatment results in (a) chan ges in host metabolism that are not mediated solely by anorexia; (b) a decrease of protein synthesis in the viscera and skeletal muscles; (c ) an increase of protein degradation in skeletal muscles; (d) reutiliz ation of leucine released from skeletal muscles in viscera, and (e) a slower disappearance rate of leucine from the blood.