| Abstract: | Development of membrane damage in erythrocytes in the presence of the radical-forming oxidant t-butylhydroperoxide is a well established fact (see, for example, Deuticke et al. (1986) Biochim. Biophys. Acta 854, 169-183). We have now demonstrated that a mere pulse treatment of erythrocytes (5-15 min) with this agent leads to subsequent development of progressive oxidative membrane damage in spite of the absence of exogenous oxidant. Damage comprises the occurrence of ion leakiness and subsequent colloid-osmotic lysis, enhancement of the transbilayer mobility of phospholipid analogues, and lipid peroxidation. There is, however, only very little concomitant oxidation and precipitation of hemoglobin. Defect formation is not due to oxidation of SH-groups nor is it directly related to lipid peroxidation, since it can be suppressed by thiourea without concommitant inhibition of lipid peroxidation. This 'spontaneous' development of membrane damage can be antagonized by metabolic substrates and by desferrioxamine, indicating that lack of protective metabolic resources as well as the presence of catalytic metal (iron) complexes are required for the development of membrane damage. This progressive development of injury in cells only temporarily exposed to an exogenous oxidant may be regarded as a more appropriate model for oxidative membrane damage under pathophysiological conditions in vivo than cells exposed to continuous damage by exogenous oxidants. |
