Endotoxin stimulates hydrogen peroxide detoxifying activity in rat hepatic endothelial cells

• Published in: Hepatology (Baltimore, Md.) Vol. 24; no. 3; pp. 691 - 696
• Main Authors: Spolarics, Z, Stein, DS, Garcia, ZC
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.09.1996
• Subjects: Animals; Endothelium, Vascular - cytology; Endothelium, Vascular - drug effects; Endothelium, Vascular - metabolism; Endotoxins - pharmacology; Fluorescence; Glucose - pharmacology; Hydrogen Peroxide - metabolism; Hydrogen Peroxide - pharmacology; Injections, Intraperitoneal; Kupffer Cells - drug effects; Kupffer Cells - physiology; Liver Circulation; Male; Nitric Oxide Synthase - antagonists & inhibitors; omega-N-Methylarginine - pharmacology; Rats; Rats, Sprague-Dawley; Tetradecanoylphorbol Acetate - pharmacology
• ISSN: 0270-9139; 1527-3350
• DOI: 10.1053/jhep.1996.v24.pm0008781344

The study aimed to assess the effect of lipopolysaccharide (LPS) in vivo (from Escherichia coli, 2 mg/kg body weight intraperitoneally) on the production and elimination of hydrogen peroxide (H2O2) in rat hepatic endothelial and Kupffer cells. Twenty-two hours after the injection of LPS, hepatic cells were isolated by collagenase and pronase digestion followed by centrifugal elutriation, and cell- associated H2O2 was determined by flow cytometry analysis using 2',7'- dichloroflorescin diacetate (DCF-diacetate). LPS treatment did not alter the basal or phorbol myristate acetate-stimulated levels of H2O2- related fluorescence in endothelial cells; however, it doubled phorbol myristate acetate-stimulated fluorescence in Kupffer cells. Administration of varying concentrations of H202 (range, 10-7 - 10-4 mol/L) in vitro caused a significantly delayed increase in fluorescence in endothelial cells from endotoxemic rats as compared with cells from saline-injected animals. The 50% effective concentration of H2O2 was found at 1.1 x 10-6 and 8.1 x 10-6 mol/L on endothelial cells after saline and LPS treatment, respectively. No differences were detected in H2O2-stimulated fluorescence between resting and LPS-stimulated Kupffer cells. Administration of varying glucose concentrations in vitro significantly decreased the H2O2- stimulated fluorescence in endothelial and Kupffer cells from LPS- injected animals. Inhibition of nitric oxide synthase by in vitro administration of NG-monomethyl-L-arginine (L-NNMMA) did not alter the H2O2- or phorbol myristate acetate-stimulated responses in endothelial and Kupffer cells. As shown earlier, LPS stimulates the gene expression of GLUT1 glucose transporter, glucose-6-phosphate dehydrogenase (G6PD), superoxide dismutases, and glutathione peroxidase in hepatic endothelial cells. The present data indicate that the LPS-induced metabolic alterations are accompanied by an increased H2O2-detoxifying capacity in hepatic endothelial cells. This may represent a protective mechanism against exogenous oxidative stress caused by activated hepatic phagocytes during inflammation. Our observations are consistent with primed production of reactive oxygen species (ROS) in LPS-activated Kupffer cells. (Hepatology 1996 Sep;24(3):691-6)