Augmented Glucose Use and Pentose Cycle Activity in Hepatic Endothelial Cells After in Vivo Endotoxemia

Glucose use and pentose cycle activity were determined in freshly isolated rat hepatic endothelial cells 3 hr after an intravenous injection of Escherichia coli lipopolysaccharide (0.1 mg/kg body weight), by use of [1-14C]glucose, [6-14C]glucose and [2-3H]glucose. Lipopolysaccharide treatment in vivo increased glucose use fivefold, whereas glucose oxidation in the pentose cycle was elevated from 0.2 to 1.5 nmol/hr/10(7) cells. In vitro incubation of endothelial cells from saline- and lipopolysaccharide-treated animals in the presence of phorbol 12-myristate 13-acetate (10(-6) mol/L) increased pentose cycle activity twofold and eightfold, respectively. Phorbol 12-myristate 13-acetate caused only a 40% to 60% increase in glycolysis in both groups. Addition of t-butyl hydroperoxide (0.5 mmol/L), a substrate for glutathione peroxidase, caused a 24-fold and 16-fold increase in the glucose flux through the pentose cycle in cells from saline- and lipopolysaccharide-treated rats, respectively. Oxidation of glucose through the Krebs cycle was also increased several-fold after t-butyl hydroperoxide administration. Depletion of cellular glutathione by N-ethylmaleimide (0.1 mmol/L) inhibited the phorbol 12-myristate 13-acetate-induced or t-butyl hydroperoxide-induced increase in the pentose cycle activity with no marked effects on glycolysis. Diphenyleneiodonium (0.1 mmol/L), an inhibitor of superoxide and nitric oxide synthesis inhibited the phorbol 12-myristate 13-acetate-induced increased pentose cycle activity with no effects on the t-butyl hydroperoxide-induced response.(ABSTRACT TRUNCATED AT 250 WORDS)