Hypoglycemic response of blood to live Escherichia coli organisms and endotoxin

Progressively developing lethal hypoglycemia in dogs and baboons subjected to endotoxin or live E. coli shock has recently been reported by this laboratory. The purpose of the present study was to explore the possibility that accelerated glycolysis in blood might contribute to the hypoglycemia of shock. Experiments were carried out on canine heparinized blood drawn from nonfasted unanesthetized animals and maintained in vitro under controlled temperature conditions. Plasma glucose was determined with a Beckman glucose analyzer. LD₁₀₀ to LD₀ doses of E. coli endotoxin or live E. coli organisms, as estimated from parallel in vivo studies, were incubated with blood during a 6- to 7-hr period. Glucose blood concentrations, cumulative glucose utilization, and dose-response studies with endotoxin and live organisms were carried out. Paired control blood samples received equal volumes of saline in place of endotoxin or organisms. All studies were conducted on the blood from a colony of seven adult mongrel donor animals. Results demonstrated consistent accelerated glucose disappearance at all doses of endotoxin and organisms, in comparison to the controls with saline only added. LD₁₀₀ experiments resulted in significantly greater disappearance rates of glucose as compared to LD₀ studies, during the first 2 hr. Minimal threshold responses for accelerated glucose utilization were observed at levels above 10⁴ organisms/ml of blood, while those for endotoxin were less than 10^-6 mg/ml, both concentrations being sublethal when applied to the whole animal. At glucose concentrations less than 20 mg%, control and experimental curves tended to converge with the achievement of minimal values of about 10 mg%. Positive correlations were seen between rates of glucose disappearance, pH, and pCO², suggesting accelerated metabolic activities by certain formed elements of the blood during the process of phagocytosis. Findings in in vitro studies were compared to those in eviscerated, nephrectomized dogs in which all sources for new glucose were eliminated, and similar accelerated rates of cumulative glucose utilization were observed between the animal and test tube experiments. Findings suggest that the excessive demand for glucose by certain blood components may explain in part the development of lethal hypoglycemia and acidemia in animals subjected to endotoxin- or live bacterial organism-induced shock.