Sepsis- and endotoxin-induced increase in organ glucose uptake in leukocyte-depleted rats

Both gram-negative infection and bacterial endotoxin (lipopolysaccharide, LPS) produce a marked neutropenia and increase glucose disposal by peripheral tissues. The purpose of the present study was to determine whether leukocyte depletion before these insults would diminish the commonly observed increases in tissue glucose uptake. Rats were depleted of circulating and marginated leukocytes with cyclophosphamide (CPA). Under basal postabsorptive conditions the subcutaneous injection of live Escherichia coli into control animals enhanced whole body glucose disposal that resulted in part from a stimulation of glucose uptake by the liver, spleen, intestine, and lung. These increases in tissue glucose uptake were not associated with an increase in neutrophil number, as assessed by myeloperoxidase (MPO) activity. CPA-induced leukopenia did not alter the sepsis-induced increase in glucose uptake by these tissues and whole body glucose use remained elevated. In contrast, skin and muscle proximal to the site of infection showed an increase in both glucose uptake and MPO activity. Furthermore, leukocyte depletion attenuated the elevated glucose uptake by skin and muscle near the inflammatory focus. The intravenous injection of LPS also increased whole body glucose disposal and enhanced glucose uptake by the lung, liver, spleen, intestine, and skin in saline-treated rats. Of these tissues the lung, liver, and spleen had a corresponding increase in neutrophil number. The LPS-induced increases in tissue glucose uptake in leukopenic rats were comparable, with the exception of liver and lung. In these tissues the incremental increase in glucose uptake after LPS was reduced 40-50% in leukopenic animals. These results indicate that, in general, the sepsis- and LPS-induced increase in glucose uptake by tissues is not because of neutrophil accumulation, except in tissues near the site of inflammation where neutrophils are actively recruited. Furthermore, leukocyte-dependent increases in tissue glucose uptake are not sufficient to elevate substantially the rate of whole body glucose use.