Transport of Paraquat by a Renal Epithelial Cell Line, MDCK

Abstract

Transport of paraquat (PQ), a herbicidal cation, was previously investigated in a proximal (LLC-PK1), renal epithelial cell line using permeable collagen-coated filters. PQ was actively transported from the basolateral side via a cation transport system by the LLC-PK1 cells. In the present study, the transport of PQ was investigated in a distal renal epithelial cell line, MDCK. PQ was predominantly transported from the basolateral to apical (B to A) side. The basolateral transport of PQ in MDCK cells was not saturable with increasing concentrations and not energy dependent. The flux and uptake of PQ was much lower in the MDCK than LLC-PK1 cells. It is concluded that MDCK, a distal renal tubular cell line, does not have an active transport system for PQ.

Reduction of paraquat-induced renal cytotoxicity by manganese and copper complexes of EGTA and EHPG

“…This uptake of paraquat is saturable with time and with increasing concentration of paraquat. It is also energy-dependent and is inhibited by certain polyvalent cations, such as quinine, cimetidine, and methylglyoxal bis(guanylhydrazine) dihydrochloride [36], [58] and [59]. The inhibitory effect of cimetidine, a divalent ion, on the uptake of paraquat into NRK-52E cells as has been shown in this study indicates the presence of a polyvalent OCT protein on NRK-52E cells and that this OCT is used by paraquat to enter NRK-52E cells.…”

“…The incubation time was based on previously published data in which the uptake of paraquat was shown to plateau after 1 h [35]. The concentrations of cimetidine and TEA used (1 mM) were based on those shown to significantly inhibit the uptake of paraquat into a renal cell line (LLC-PK 1 ) [36]. Concentrations of Mn(II) and Cu(II) complexes of EGTA and EHPG were based on those providing significant reduction of paraquat toxicity based on the data obtained from biochemical assays measuring cellular viability and cell death.…”

Hepatic Disposition of Neurotoxins and Pesticides

“…Although the data are difficult to interpret because the paraquat outflow curves were nearly superimposed upon the sucrose curves, they suggest that there may be a specific efflux transport mechanism for paraquat. Paraquat is a cationic herbicide transported by the organic cation transporter in a renal epithelial cell line, LLC-PK 1 (Chan et al 1996a) and rat renal proximal tubular cells (Chan et al 1996b). Additionally, paraquat is taken up into type II alveolar epithelium of the lung via the polyamine transport system (Hoet et al 1995).…”

Modulation of Antioxidant Enzyme Expression and Activity by Paraquat in Renal Epithelial NRK-52E Cells

“…The incorporation of [ 3 H]-thymidine and [ 3 H]-leucine into NRK-52E cells was performed as described previously for renal cell cultures (Chan et al, 1996;Chatterjee et al, 1997) and used for the estimation of DNA and de novo protein synthesis respectively. Briefly, confluent NRK-52E cells grown in 6-well plates were incubated with DMEM only and DM containing 30 or 1mM PQ for 4 and 24 hours respectively.…”