Cytotoxicity of mercury compounds in LLC-PK1, MDCK and human proximal tubular cells

Abstract

Six mercury compounds [HgCl2 (MC), Hg(CH3COO)2 (MA), Hg(NO3)2 (MN), C2H5HgSC6H4COONa (EMT), C6H5HgOCOCH3 (PMA) and CH3CIHg (MMC)] were studied using two kidney cell lines (MDCK and LLC-PK1), primary cultures of human proximal tubular cells (hPTC) and nonrenal cell lines (SAOS and Hep G2). Cell damage was measured with four different tests: neutral red uptake, mitochondrial dehydrogenase activity (MTT conversion), thymidine incorporation and protein content. Relative toxicity was established by the determination of the concentration of test compound inducing a 50% reduction of the parameter considered (EC50 value). Two groups could be distinguished: PMA, EMT and MMC are one order of magnitude more toxic than MC, MN and MA. Cellular uptake was measured by the HPLC-hybrid generation AAS after 24 hours treatment with 1.5 microM MC, MMC, PMA or EMT in MDCK cells, revealing Hg concentrations of 42.8 +/- 2.5 ng/mg protein for MC, 596.9 +/- 87.8 ng/mg protein for MMC, 269.8 +/- 75.7 ng/mg protein for PMA and of 115.9 +/- 25.2 ng/mg protein for EMT. Cytotoxicity was positively correlated with cellular uptake. The effect of the cellular GSH content on the toxicity of mercury was studied using the GSH synthesis inhibitor L-buthionine sulfoximine (BSO). In all cases an enhanced cytotoxicity was observed after BSO treatment. 2-Oxo-4-thiazolidine carboxylic acid (OTC) was used as a substrate for the GSH synthesis. Although OTC did not enhance the GSH content, the cytotoxicity of MC, MN and MA decreased significantly, no changes were observed for the other mercurials.(ABSTRACT TRUNCATED AT 250 WORDS)

Antioxidant potential and gap junction-mediated intercellular communication as early biological markers of mercuric chloride toxicity in the MDCK cell line

“…This event, dose and time related, could depend on an early activation of the GSH synthesis. This may, in fact, represent the mechanism by which the cells, ''neutralising'' the free mercuric ions, are able to reduce their toxic effect (Miura and Clarkson, 1993;Bohets et al, 1995). On the other hand, due to the high affinity of Hg 2+ for the thiol, the formation of Hg-GSH complexes could strongly decrease the intracellular concentration of the free tripeptide, thus affecting (reducing) the total cell redox potential (see, for example, Zalups and Lash, 1990;Lash and Zalups, 1992).…”

“…Since tubular epithelium represents the primary target of inorganic mercurials, this cell line was particularly suitable to our aim. This line has, in fact, well-known tubular differentiated properties, and for that reason it has been used extensively as a valuable in vitro model for studying tubular function and xenobiotic-induced nephrotoxicity (including that due to heavy metals) (Bohets et al, 1995;Prozialeck and Lamar, 1998).…”

L-arginine Reduces Mercury Accumulation in Thymus of Mercury-exposed Mice: Role of Nitric Oxide Synthase Activity and Metallothioneins

“…Since mercury ions have a high affinity for sulfhydrylcontaining molecules such as cysteine (Cys) 31) , Hg 2+ in mercury-exposed thymus is believed to bind to Cys-rich MT-I and to accumulate in the organ 20) . Indeed, MT-I mRNA expression in whole thymus was significantly raised in mice exposed to both Hg 2+ doses.…”

DMPS reverts morphologic and mitochondrial damage in OK cells exposed to toxic concentrations of HgCl2

“…Mercury toxicity is related to its capacity to interact with functional groups, proteins or DNA, which lead to activation/inactivation of transcription factors, induction of adduct formation, or inhibition of the cellular metabolism. The effects of mercury are reflected as alterations of the cellular membrane, induction of chromosomal aberrations, inhibition of cell cycle and protein synthesis, and damage to the mitochondria (Nakazawa et al, 1975;Bohets et al, 1995;Königsberg et al, 2001).…”