Early changes in glucose utilization of individual tissues after endotoxin administration

Administration of Escherichia coli endotoxin (100 micrograms/100 g, i.v.) to conscious rats induces transient hyperglycemia and a sustained increase in whole body glucose turnover. To identify the tissues responsible for the increase in glucose utilization, the glucose metabolic rate (Rg) of peripheral tissues was determined in vivo by the 2-deoxyglucose tracer technique during and after the hyperglycemic phase. Rg was markedly increased in spleen, liver, intestine, epidydimal fat, gastrocnemius muscle, and skin during the early hyperglycemic period (80 min after endotoxin) and remained elevated in the subsequent euglycemic period (220 min). Combined alpha- and beta-adrenergic blockade, achieved by the primed continuous infusion of phentolamine and propranolol, prevented the transient hyperglycemia that followed endotoxin injection. Adrenergic blockade also prevented or considerably attenuated the early increases in tissue glucose utilization that were induced by endotoxin. The results indicate that the early increase in Rg can be mainly attributed to adrenergic stimulation and the resultant hyperglycemia, while the sustained elevation is due to mechanisms independent of hyperglycemia.