SUSTAINED MODIFICATIONS OF PROTEIN-METABOLISM IN VARIOUS TISSUES IN ARAT MODEL OF LONG-LASTING SEPSIS

1. Sepsis was induced in rats by an intravenous injection of live bact eria, Infected and pair-fed animals were studied before the infection, in an acute septic phase (day 2 post-infection), in a chronic septic phase (day 6) and in a late septic phase (day 10), Protein synthesis r ates were measured in vivo after administration of a flooding dose of L[1-C-13] valine. 2. During the acute phase, muscle protein loss assoc iated with infection resulted from both a decrease in protein synthesi s and an increase in proteolysis, During the chronic phase and the lat e phase, the increase of proteolysis in infected rats as compared with pair-fed animals persisted, worsening muscle atrophy Skin protein syn thesis rates were not significantly modified by infection. However, sk in protein content decreased 6 and 10 days after infection, suggesting an increased proteolysis in response to sepsis. 3. Protein synthesis in liver of infected rats was twice that of pair-fed animals. Liver pr otein synthesis remained elevated in infected rats compared with pair- fed animals until day 10, Hypoalbuminaemia and high plasma concentrati ons of fibrinogen were evident at all periods studied. alpha(2)-Macrog lobulin and alpha(1)-acid glycoprotein reached peak concentrations dur ing the acute phase (concentrations increased 50 times in infected rat s). On day 10, the levels of these proteins were still about 12-fold h igher. 4. Protein synthesis rates were significantly increased in the digestive tract and lung of infected rats compared with pair-fed group s on days 2 and 6, but were similar in the two groups on day 10 postin fection. The fractional protein synthesis rate was increased 3-fold ov er the entire experimental period in the spleen. 5. The results show t hat sepsis stimulates protein synthesis in various tissues over a long time, and that skin, like muscle, can provide amino acids to the rest of the body.