Exposure to low- vs iso-osmolar contrast agents reduces NADPH-dependent reactive oxygen species generation in a cellular model of renal injury.

Abstract Contrast-induced nephropathyrepresents the third cause of hospital-acquired acute renal failure. This study investigated the effects of low- vs iso-osmolar contrast medium (CM) exposure on NADPH-dependent reactive oxygen species (ROS) generation by tubular cells. X-ray attenuation of iohexol, iopamidol, and iodixanolwas assessed at equimolar iodine concentrations and their effects on human renal proximal tubular cells (PTCs) were evaluated with equally attenuating solutions of each CM. Cytotoxicity, apoptosis, and necrosis were investigated by trypan blueexclusion, MTT assay, and annexin V/ propidium iodideassay, respectively. ROS production was assessed by DCF assay, NADPH oxidaseactivity by the lucigenin-enhanced chemiluminescence method, and Nox4expression by immunoblot. Yielding the same X-ray attenuation, CM cytotoxicity was assessed in PTCs at equimolar iodine concentrations. More necrosis was present after incubation with iohexoland iopamidolthan after incubation with equal concentrations of iodixanol. Iohexoland iodixanolat low iodine concentrations induced less cytotoxicity than iopamidol. Moreover, both iohexoland iopamidolinduced more apoptosis than iodixanol, with a dose-dependent effect. ROS generation was significantly higher with iopamidoland iohexolcompared to iodixanol. NADPH oxidaseactivity and Nox4protein expression significantly increased after exposure to iopamidoland iohexol, with a dose-dependent effect, compared with iodixanol. CM-induced Nox4expression and activity depended upon Src activation. In conclusion, at angiographic concentrations, iodixanolinduces fewer cytotoxic effects on cultured tubular cells than iohexoland iopamidolalong with a lower induction of Nox4-dependent ROS generation. This enzyme may, thus, represent a potential therapeutic target to prevent iodinated CM-related oxidative stress.