Reduced H2O2 Production Research Articles

Arginine Administration Reduces Hydrogen Peroxide in Ischemia-reperfusion Endothelium of Rats.

L-Arg as a precursor of nitric oxide (NO) can be used in experiments to observe the action of NO. The present work is aimed at exploring the effect of oral administration of L-Arg on the ischemia-reperfusion (IR) damage of endothelial cells (EC) and the clearance of reaction oxygen species in the IR carotid artery. Cerium-marked cytochemical technique was used to localize the H2O2 product in endothelium. The area of Ce-H2O2 denseprecipitate on the lumen surface of damaged endothelium per length of artery wall (nm2/nm) was measured. It was found that the dense precipitate was decreased to 102.1±27.6 in rats drinking tap water containing 2.5% L-arginine for 3 days, much less than in control rats drinking tap water only (203.7±31.8, p<0.01). Furthermore, the IR damage of EC was relieved markedly. Drinking tap water containing D-Arg or L-Lys had no effects either on the amount of dense precipitate or on the EC damage. NG-nitro- L-arginine methyl ester, an inhibitor of NO synthase, decreased the effect of L-Arg markedly. These results indicate that L-Arg administration can reduce H2O2 production in the IR artery, and thus IR damage of EC is alleviated.

Neutrophil adherence to isolated adult canine myocytes. Evidence for a CD18-dependent mechanism.

Cardiac myocytes were isolated from adult dogs and incubated with isolated canine neutrophils (PMN). Intercellular adhesion was low and unchanged by stimulation of the PMN with zymosan activated serum or platelet activating factor (PAF) at concentrations that significantly enhance PMN adhesion to protein-coated glass and canine endothelial cell monolayers. Intercellular adhesion was significantly increased only when both myocytes and PMN were stimulated (e.g., myocytes incubated with IL-1, tumor necrosis factor, or phorbol myristate acetate, and PMN were chemotactically stimulated). Inhibitors of protein synthesis diminished the IL-1 beta-induced effect by greater than 80%. The IL-1 beta, PAF-stimulated PMN-myocyte adhesion was associated with substantial H2O2 production. Under conditions with low PMN-myocyte adhesion (i.e., IL-1 beta alone, PAF alone, or no stimulus) H2O2 production was generally less than 5% of that occurring with high adhesion. An anti-CD18 monoclonal antibody (R15.7) inhibited stimulated PMN-myocyte adhesion by greater than 95% and reduced H2O2 production by greater than 90%. Control isotype-matched, binding, and nonbinding antibodies were without effect on adherence or H2O2 production. The results indicate that cytokine stimulation of adult myocytes induces expression of a ligand involved in CD18-dependent adherence of canine neutrophils.

Photolysis of Water Vapor

The photolysis of water vapor has been studied in a flow system at rates up to 5 mole hr—1 and at temperatures up to 540°K under the influence of hydrogen discharge radiation around 1650 A. The products H2, O2 and H2O2 varied in amounts and proportions depending on the geometry of the system. Rapid removal of the products of photolysis from the reaction zone to a liquid N2 trap favored H2O2 production. Resultantly the quantum yield also varied with the geometry of the system, values from 0.03 to 0.3 were obtained. He as a diluent caused a decrease in H2O2 production. Added H2 reduced H2O2 production tenfold, accounted for by its reaction with OH. A mechanism is discussed which is substantiated by a study of the dependence of the reaction rates on light intensity.