Involvement of reactive oxygen species on gentamicin-induced mesangial cell activation

Abstract

Background. Reactive oxygen species (ROS) have been shown to be involved in the reduction of glomerular filtration rate observed after gentamicin (Genta) treatment in vivo, a phenomenon directly related with mesangial cell (MC) contraction. Our previous study reported that Genta induces concentration-dependent MC contraction and proliferation in vitro. Methods. To study the possible mediation of ROS in the effect of Genta, ROS production was measured in primary cultures of rat MC stimulated with Genta (10-5 mol/L). In addition, the MC response to Genta in the presence of the ROS scavengers superoxide dismutase (SOD) and catalase (CAT) was studied. MC activation and O2- production were studied in the presence of an inhibitor of the NADP(H) oxidase, diphenylene iodinium (DPI), and in the presence of L-NAME, an inhibitor of nitric oxide synthases (NOS). Finally, the effects of Genta on SOD activity and mRNA expression were examined. Results. Genta (10-5 mol/L) induced an increase in O2- production and SOD activity that was neither accompanied by an elevation in cytosolic Cu/Zn-SOD mRNA expression nor by H2O2 accumulation. Genta induced MC contraction and proliferation that were inhibited by SOD plus CAT. Both the extracellular and intracellular ROS donor systems, xantine+xantine oxidase (X+XO) and dimethoxinaphtoquinone (DMNQ), respectively, also stimulated MC contraction and proliferation. Genta-induced MC activation and O2- production were inhibited by DPI. Genta-induced O2- production was inhibited by L-NAME. Furthermore, Genta did not induce detectable changes in membrane fluidity and lipid peroxidation. Conclusions. These results strongly suggest that an oxidative-mediated pathway exists in Genta-induced MC activation. A portion of the production of O2- may be due to NADP(H) oxidase and NOS activation. The amount of ROS produced, rather than having a toxic effect, might play a role as a mediator of Genta-induced MC activation.