Reactive oxygen species independent cytotoxicity induced by radiocontrast agents in tubular cells (LLC-PK1 and MDCK).
OBJECTIVE
Radiocontrast agents (RAs) cause renal tubular damage by hemodynamic imbalance, which could cause hypoxic stimulus and direct cytotoxicity. However, reactive oxygen species (ROS) could be an important factor in RAs' direct cytotoxicity. This study investigated the involvement of ROS in deleterious effects produced by RAs on normoxic and hypoxic renal tubular cells.


METHODS
LLC-PK1 and MDCK were exposed to diatrizoate and ioxaglate in normoxic and hypoxic conditions. Apoptotic and necrotic cell death were assessed by acridine orange/ethidium bromide and annexin V methods. Hydrogen peroxide, superoxide anion, and malondialdehyde levels were analyzed by, respectively, 2',7'-dichlorofluorescein, luminal, and thiobarbituric acid. Antioxidant agents were used to prevent cellular RAs damage.


RESULTS
Diatrizoate and ioxaglate decreased cellular viability in both cells, and this effect was enhanced by hypoxic conditions. Diatrizoate induced more injury than ioxaglate to both cell lines. LLC-PK1 underwent necrosis, while MDCK cells underwent apoptosis when exposed to diatrizoate. These results could not be attributed to an increase in osmolality. RAs did not increase hydrogen peroxide, superoxide anion or malondialdehyde levels in both cells. Additionally, N-acetyl-L-cysteine (NAC), ascorbic acid, alpha-tocopherol, glutathione, beta-carotene, allopurinol, cimetidine, and citric acid did not protect cells against RAs damage. Surprising, NAC increased the cellular damage induced by ioxaglate in the both cell lines.


CONCLUSIONS
The present study shows that RAs induce damage in cultured tubular cells, especially in hypoxic conditions. ROS were not involved in the observed RAs' cytotoxicity, and NAC increased ioxaglate-induced tubular damage.
Garofalo
Andrezza Sanches
AS
Nephrology Division, Medicine Department, Universidade Federal de São Paulo (UNIFESP), São Paulo, Brazil.
Borges
Fernanda Teixeira
FT
Dalboni
Maria Aparecida
MA
Pavão dos Santos
Oscar Fernando
OF
D000111:Acetylcysteine / Q000494:pharmacology; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D015687:Cell Hypoxia; D002460:Cell Line; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects* / Q000528:radiation effects; D003287:Contrast Media; D004285:Dogs; D007668:Kidney; D007770:L-Lactate Dehydrogenase / Q000032:analysis; D008175:Lung Neoplasms; D009336:Necrosis; D011868:Radioisotopes / Q000494:pharmacology; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013552:Swine
D000975:Antioxidants; D003287:Contrast Media; D011868:Radioisotopes; D017382:Reactive Oxygen Species; D007770:L-Lactate Dehydrogenase; D000111:Acetylcysteine