Proximal tubule cell response to radiographic contrast media

Renal dysfunction associated with contrast media (CM) administration is gen erally attributed to reduced renal blood flow. Studies, however, also sugge st direct tubular effects of CM, whose mechanisms remain unclear. This stud y was conducted to assess the chemotoxic effects of iopamidol, a prototypic CM, on a porcine proximal tubule (PT) cell line, LLC-PK1 cells. Results in dicate that iopamidol did not affect cell viability (determined by trypan b lue exclusion and fluorescein staining), but did reduce cell proliferation. Moreover, iopamidol altered mitochondrial function, as determined by 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) reduction and mitochondrial membrane potential. Decreased MTT reduction was evident with all CM tested, and its rapid recovery after CM removal suggests that inhib ition of mitochondrial function is reversible. Injury to PT cells by iopami dol is supported by the fact that CM increase extracellular adenosine, an i ndicator of cellular stress. This study provides greater insight into the m echanism underlying the nephrotoxicity induced by contrast in patients and explains the reversibility of this toxicity.