Superoxide dismutase in rats with sepsis. Effect on survival rate and amino acid transport.

In a recent study, administration of the free radical scavenger superoxide dismutase (SOD) improved survival in rats with sepsis when administered two hours before induction of sepsis. The present study was designed to determine whether free radical-induced membrane damage is involved in the pathogenesis of decreased muscle amino acid uptake, noted in sepsis. Additionally, the effect on survival rate of SOD given after the onset of sepsis was studied. Sepsis was induced by cecal ligation and puncture in rats. Amino acid transport in incubated soleus muscles was studied using tritiated alpha-aminoisobutyric acid. Amino acid uptake was significantly reduced in muscle from rats with sepsis. Administration of SOD before induction of sepsis or added in vitro to incubated muscles with sepsis had no effect on alpha-aminoisobutyric acid uptake. Survival rate was not increased when SOD was given two hours after cecal ligation and puncture. The results suggest that free radical-induced membrane damage is not the mechanism of inhibited muscle amino acid transport in sepsis. Since survival was not improved by SOD administered after induction of sepsis, the role of the enzyme in the treatment of sepsis may be questioned.