Exposure of human erythrocytes to oxygen radicals causes loss of deformability, increased osmotic fragility, lipid peroxidation and protein degradation

The effects of two oxygen radical generating systems (H2O2 and ascorbate/Fe +2) on erythrocyte deformability, osmotic fragility, lipid peroxidation and protein degradation were studied. Incubation of erythrocytes with differen t concentrations of H2O2 (5-20 mM) or ascorbate/Fe+2 (10/0.1-40/0.4 mM) cau sed a loss of deformability and increased osmotic fragility. The loss of de formability has occurred in a dose-dependent fashion and was proportional t o the extent of malonyldialdehyde (an indicator of lipid peroxidation) and alanine production (an indicator of protein degradation). Prior exposure of the erythrocytes to carbon monoxide (known to inhibit heme-protein degrada tion) prevented almost completely the loss in deformability caused by H2O2, indicating that the loss in deformability was due mainly to protein degrad ation rather than to lipid peroxidation. Erythrocytes incubated with either of the two systems have also shown morphologic changes characterized by a dose-dependent increase in echinocyte formation. The results indicate the i mportance of oxidatively damaged proteins in compromising the theologic beh aviour of the erythrocytes, particularly when the free radicals are involve d.