Exdotoxin-induced metabolic changes in the conscious, unrestrained rat: hypoglycemia and elevated blood lactate concentrations without hyperinsulinemia.

The effects of E coli endotoxin on the plasma concentrations of glucose, lactate, and immunoreactive insulin (IRI) were studied in conscious unrestrained rats. Additionally the effects of endotoxin on glucose-induced elevations in the plasma IRI concentration and on the rate of disappearance of an intravenous glucose load were examined. After a transient and small hyperglycemia endotoxin administration resulted in a progressive, dose-dependent decrease in the plasma glucose concentration and a marked elevation of plasma lactate. The initial hyperglycemia was accompanied by a small, transient increase in the plasma IRI concentration. There was no increase in the plasma IRI concentration during the development of hypoglycemia. The hypoglycemic effect of endotoxin was fully manifest in streptozotocin diabetic rats which displayed low insulin concentrations initially and throughout the experiment. Endotoxin injection produced a significant reduction in the plasma IRI response to glucose administration and a decrease in the rate of disappearance of a glucose load. It is suggested that the metabolic effects of endotoxin in the rat are not mediated by an increase in insulin secretion.