Direct effects of gram-negative endotoxin on skeletal muscle glucose uptake

The effect of locally infused endotoxin on gracilis muscle glucose uptake was determined in anesthetized mongrel dogs. Locally infused endotoxin consistently caused an increase in skeletal muscle glucose uptake with no alterations in any other metabolic variable. These data demonstrate that endotoxin can act locally to increase glucose uptake by skeletal muscle, independent of the action of insulin or other metabolic factors. On the other hand, when endotoxin was given systemically to induce shock, gracilis muscle glucose uptake did not increase. These differences may reflect the reduction in plasma endotoxin concentration mediated by the reticuloendothelial system (RES). However, live Escherichia coli shock was associated with an increase in glucose uptake in the constant flow perfused gracilis muscle after 4.5 h of shock. We believe this increase in muscle glucose uptake resulted from the direct effects of endotoxin, the plasma concentration of which presumably increased as the RES was overwhelmed and became less effective. The contribution of this phenomenon to the hypoglycemia of gram-negative endotoxin or septic shock cannot be evaluated from this study.