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

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