Reduced glutathione protect cells from ouabain toxicity

It is widely accepted that a prolonged ouabain blockade of the Na+,K+-ATPas e makes cells detach from each other and from the substrate, leading to the ir death and that cellular resistance to ouabain is due to the presence of isoforms of Na+,K+-ATPase with low affinity to this glycoside. In the prese nt work the effect of reduced glutathione in the response of two types of r enal cells to ouabain: MDCK, a ouabain-sensitive cell line and Ma104, a oua bain-resistant one, was studied. Glutathione protected MDCK cells from ouab ain toxicity and inhibition of glutathione synthesis by L-buthionine-S,R-su lfoximine sensitized Ma104 cells to ouabain. As glutathione is involved wit h multidrug resistance (MDR) in cells expressing the multidrug resistance-r elated protein MRP1 and as Ma104 cells have a MDR phenotype, it was investi gated whether Ma104 cells express this protein. The expression of the MRP1- mRNA in Ma104 cells was detected by reverse transcriptase-polymerase chain reaction and ribonuclease protection assay, and the protein was detected by Western blotting and immunofluorescence. Treatment of Ma104 cells with oua bain increased MRP1-mRNA expression and altered the localization of MRP1 in these cells. Our results suggest that some cells may have mechanisms to pr otect themselves from ouabain toxicity and that MRP1 may have a role in con trolling the toxic effects of ouabain. (C) 2001 Elsevier Science B.V. All r ights reserved.