Hydrogen peroxide-induced cell and tissue injury: Protective effects of Mn 2+

Abstract

Recent evidence indicates that under in vitro conditions, superoxide anion and hydrogen peroxide (H 2 O 2 ) are unstable in the presence of manganese ion (Mn 2+ ). The current studies snow that in the presence of Mn 2+ , H 2 O 2 -mediated injury of endothelial cells is greatly attenuated. A source of bicarbonate ion and amino acid is required for Mn 2+ to exert its protective effects. Injury by phorbol ester-activated neutrophils is also attenuated under the same conditions. EDTA reverses the protective effects. Acute lung injury produced in vivo in rats by intratracheal instillation of glucose-glucose oxidase is almost completely blocked in rats treated with Mn 2+ and glycine. Conversely, treatment of rats with EDTA, a chelator of Mn 2+ , markedly accentuates lung injury caused by glucose-glucose oxidase. These data are consistent with the findings of others that Mn 2+ can facilitate direct oxidation of amino acids with concomitant H 2 O 2 disproportionation. This could form the basis of a new therapeutic approach against oxygen radical-mediated tissue injury.