Electron paramagnetic resonance studies of membrane fluidity in ozone-treated erythrocytes and liposomes

Doxyl stearate spin probes which differed in the attachment of the nitroxid e free radical to the fatty acid have been used to study membrane fluidity in ozone-treated bovine erythrocytes and liposomes. Analysis of EPR spectra of spin labels incorporated into lipid bilayer of the erythrocyte membrane s indicates an increase in the mobility and decrease in the order of membra ne lipids, in isolated erythrocyte membranes (ghosts) the most significant changes were observed for 16-doxylstearic acid. In intact erythrocytes stat istically significant were differences for 5-doxylstearic acid. The effect of ozone on liposomes prepared from a lipid extract of erythrocyte lipids w as marked in the membrane microenvironment sampled by all spin probes. Ozon e apparently leads to alterations of membrane dynamics and structure but do es not cause increased rigidity of the membrane.