Bilirubin‐photosensitized Lysis of Resealed Erythrocyte Membranes*

The ability of bilirubin to photosensitize biomembrane damage has been tested, using resealed human erythrocyte ghosts as a model system. Continuous irradiation of bilirubin‐charged ghosts with broad‐band blue light resulted in membrane lysis, as evidenced by the release of trapped markers such as Na+ or glucose‐6‐phosphate. Sodium dodecyl sulfate‐gel electrophoresis of membrane proteins revealed a progressive and relatively rapid loss of spectrin (bands 1 and 2) and band 4.1 during irradiation, accompanied by the appearance of cross‐linked polypeptides. The antioxidant butylated hydroxytoluene protected ghosts against lysis, but not against protein cross‐linking, suggesting that lipid peroxidation is the crucial membrane disrupting event.