PRIMED PENTOSE CYCLE ACTIVITY SUPPORTS PRODUCTION AND ELIMINATION OF SUPEROXIDE ANION IN KUPFFER CELLS FROM RATS TREATED WITH ENDOTOXIN IN-VIVO

Glucose use and pentose cycle activity were determined in freshly isol ated rat Kupffer cells 3 h after an i.v. injection of Escherichia coli endotoxin (0.1 mg/kg body weight), by using [1-C-14], [6-C-14] and [2 -H-3]glucose. Endotoxin treatment in vivo caused a 5-fold increase in the basal glucose uptake in Kupffer cells. Pentose cycle activity was elevated from 8.7 to 13.6 nmol/h per 10(7) cells after endotoxin. In v itro treatment of the cells from saline- and endotoxin-treated animals with phorbol ester (10(-6) M) increased pentose cycle activity 2-fold and 8-fold, respectively. Phorbol ester caused a 50% increase in gluc ose uptake in both groups. t-Butyl hydroperoxide (0.5 mM) caused a sim ilar increase in pentose cycle activity as phorbol ester. Glucose oxid ation in the Krebs cycle was also doubled after endotoxin. KC from end otoxin-treated animals produced O-2(-) spontaneously, and were primed to produce additional large amounts of O-2(-) upon phorbol ester treat ment. Addition of t-butyl hydroperoxide inhibited O-2(-) production by Kupffer cells. Depletion of glutathione by N-ethylmaleimide (0.1 mM), or inhibition of NADPH oxidase by diphenyliodonium (0.1 mM) inhibited both the pentose cycle activity and the O-2(-) production. Increasing the concentration of exogenous glucose in the cell medium elevated th e glycolytic rate, while pentose cycle flux was not affected either un der basal conditions or following subsequent challenges by phorbol est er or t-butyl hydroperoxide. Our data suggest that the endotoxin-induc ed elevated glucose use in Kupffer cells is accompanied by a primed st ate of the pentose cycle. This condition supports superoxide and macro molecule synthesis and could also represent a potentiated protective m echanism against oxidative cellular injury during bacterial infections .