ALTERATIONS IN MEMBRANE FLUIDITY, SUPEROXIDE-DISMUTASE ACTIVITY AND LIPOPEROXIDE CONTENT IN MONOCYTIC CELL-LINE U937 CULTURED WITH TERT-BUTYL HYDROPEROXIDE IN-VITRO

Reactive oxygen species have been implicated in the pathogenesis of va rious hyperproliferative diseases. Monocyte adhesion to the vascular e ndothelial cell, an important component in the inflammatory response, is one of the earliest detected events in the pathogenesis of atherosc lerosis; Data presented here demonstrate the changes in superoxide dis mutase (SOD, EC 1.15.11) activity, lipoperoxide (LPO) content and flui dity of the plasma membrane in monocytic cell line U937 cultured with tert-butyl hydroperoxide (tbOOH) conditional medium. After culture in vitro with tbOOH for 24 and 48 h, the content of LPO in these cells in creased and the activity of SOD and fluidity of plasma membrane decrea sed. The results reveal dose- and time-de pendent effects, i.e., the h igher concentration of the tbOOH and the longer the incubation time, t he more marked the changes. These alterations in monocytic cell line U 937 induced by tbOOH in vitro indicate that lipoperoxidative damage mi ght be the main cause of the damage to monocyte in the atherosclerosis .