Reactive Oxygen Species Independent Cytotoxicity Induced by Radiocontrast Agents in Tubular Cells (LLC-PK1 and MDCK)

Abstract

Purpose. 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. Materials and 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, α-tocopherol, glutathione, β-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. Conclusion. 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.

N-Acetylcysteine Amide Protects Renal Proximal Tubular Epithelial Cells against Iohexol-Induced Apoptosis by Blocking p38 MAPK and iNOS Signaling

“…It has recently been reported that RCM induce caspase-dependent apoptotic injury both in glomerular cells and renal tubular epithelial cells, and that proximal tubular cells seem more sensitive to RCM cytotoxicity comparing with distal tubular cells [3,5,6]. Although these findings suggest that apoptosis is associated with the pathophysiology of CIN, the selective regulation of apoptosis is not fully understood [7]. …”

“…Several studies have reported that RCM induce caspase-dependent apoptosis in glomerular and tubular epithelial cells in vitro [3,5,6]. Although these findings suggest that apoptosis is involved in the pathophysiology of CIN, the mechanism that initiates apoptosis after exposure to RCM is poorly understood [7]. Caspase-dependent apoptosis can be mediated by the free radical nitric oxide (NO), which is generated during the conversion of L -arginine to citrulline by nitric oxide synthase (NOS) enzymes [8,9,10].…”

Methylguanidine cytotoxicity on HK-2 cells and protective effect of antioxidants against MG-induced apoptosis in renal proximal tubular cellsin vitro

“…Apoptosis of renal cells induced by some substances such as radiocontrast agents, hypoxia, albumin, aristolochic acid, adriamycin, and gentamicin has been widely reported. [38][39][40][41][42][43] However, the role of uremic toxins in inducing renal intrinsic apoptosis during progressive nephron deprivation in chronic renal insufficiency has been reported less frequently. Our present study was to examine whether the increased level of MG in the plasma of CRF patients induces apoptosis in renal proximal tubular cells and investigate some pharmacological interventions of this cell apoptosis in vitro.…”

Renal cell apoptosis induced by nephrotoxic drugs: cellular and molecular mechanisms and potential approaches to modulation

“…Cidofovir Human tubules/HK-2 [144] Cisplatin Mouse PTC [71,171,180] Mouse CDC [181] Cyclosporine A MDCK [182] Rat: subcortical and juxtamedullary kidney sections [179] Tubular and interstitial cells [ Endotoxins Human tubular epithelial cells [185,186] Mice (Fas-/-, TNFR1-/-TNFR2-/-) [187] C3H/HeJ Mice [188] Fluoroquinolones Human: distal tubular cells [189] Mercuric chloride Cultured rat proximal tubular cells (WKPT) [178] LLC-PK1 [190] Microcystin Rat: kidney cortex and medulla [191] Ochratoxin A PRK [192] OK [193] NRK-52E [193] Oxalate MDCK [194] Radio-contrast agents MDCK [195][196][197] LLC-PK1 [197,198] …”