Liposomes as a model for studying the effect of UV radiations on biomembranes

Sonicated vesicles prepared from lecithin and rat brain or liver lipid extracts were exposed to ultraviolet radiations (UV), and the formation of thiobarbituric acid reactive products of lipid peroxidation were followed. Long range UV (UVA) was found to be more active than short UV (UVC). Incorporation of different amounts of pure Cu-Zn superoxide dismutase, caused a consistent increase in thiobarbituric acid reactive products in the case of UVC, but with UVA, higher doses were inhibitory. Incorporation of alpha-tocopherol into the vesicles, helped to entrap more calcium ions within the dialysed liposomes, but UV exposure did not significantly influence calcium leakage. Liposomes appear to be convenient in vitro models for studying the phototoxic effects mediated through active oxygen species, membrane damage and altered calcium fluxes.