Insulin protects against muscle proteolysis induced by septic plasma
L. Mitchell and L. W. Norton
Surgical Service, VA Medical Center, Denver, CO 80220.
Sepsis, like trauma, causes proteolysis of skeletal muscle. Insulin
normally protects against muscle protein degradation. In earlier work using
a rat muscle preparation, insulin inhibition of proteolysis decreased in
the presence of plasma from injured patients. The current experiments
tested the effect of plasma from septic patients on insulin inhibition in
the same model. The mean value of protein degradation among eight septic
plasma samples was 49% greater than the mean value among five normal plasma
samples in soleus muscle and 45% greater in extensor digitorum longus
muscle. In the presence of insulin, 10(3) mU/L, the increases in
degradation with septic plasma were 42% in soleus muscle and 48% in
extensor digitorum longus muscle. Insulin reduced degradation an average of
6% (soleus) and 10% (extensor digitorum longus) in normal plasma and 10%
(soleus) and 8% (extensor digitorum longus) in septic plasma. In contrast
to results of other studies, these experiments show that the protective
effect of a moderate concentration of insulin in resisting muscle protein
degradation is not significantly different in the muscle protein
degradation is not significantly different in the presence of septic human
plasma compared with normal plasma. This finding supports clinical efforts
to decrease proteolysis in septic patients by the administration of
insulin.