Inhibition of Na+,K+-ATPase by ouabain triggers epithelial cell death independently of inversion of the [Na+]i/[K+]i ratio.
Treatment with ouabain led to massive death of principal cells from collecting ducts (C7-MDCK), indicated by cell swelling, loss of mitochondrial function, an irregular pattern of DNA degradation, and insensitivity to pan-caspase inhibitor. Equimolar substitution of extracellular Na(+) by K(+) or choline(+) sharply attenuated the effect of ouabain on intracellular Na(+) and K(+) content but did not protect the cells from death in the presence of ouabain. In contrast to ouabain, inhibition of the Na(+)/K(+) pump in K(+)-free medium increased Na(+)(i) content but did not affect cell survival. In control and K(+)-free medium, ouabain triggered half-maximal cell death at concentrations of approximately 0.5 and 0.05 microM, respectively, which was consistent with elevation of Na(+)/K(+) pump sensitivity to ouabain in K(+)-depleted medium. Our results show for the first time that the death of ouabain-treated renal epithelial cells is independent of the inhibition of Na(+)/K(+) pump-mediated ion fluxes and the [Na(+)](i)]/[K(+)](i) ratio.
Pchejetski
Dimitri
D
Centre de recherche, Centre hospitalier de l'Université de Montréal, Hôtel-Dieu, PQ, Canada
Taurin
Sebastien
S
Der Sarkissian
Shant
S
Lopina
Olga D
OD
Pshezhetsky
Alexei V
AV
Tremblay
Johanne
J
deBlois
Denis
D
Hamet
Pavel
P
Orlov
Sergei N
SN
D000818:Animals; D002118:Calcium / Q000502:physiology; D016923:Cell Death; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D003513:Cycloheximide / Q000494:pharmacology; D003609:Dactinomycin / Q000494:pharmacology; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D004847:Epithelial Cells / Q000737:chemistry / Q000166:cytology / Q000187:drug effects / Q000201:enzymology; D017136:Ion Transport; D007685:Kidney Tubules, Collecting / Q000737:chemistry / Q000166:cytology* / Q000201:enzymology*; D007700:Kinetics; D019384:Nucleic Acid Synthesis Inhibitors / Q000494:pharmacology; D010042:Ouabain / Q000494:pharmacology*; D011188:Potassium / Q000032:analysis; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D012964:Sodium / Q000032:analysis; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors*
D004791:Enzyme Inhibitors; D019384:Nucleic Acid Synthesis Inhibitors; D011500:Protein Synthesis Inhibitors; D003609:Dactinomycin; D010042:Ouabain; D003513:Cycloheximide; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium; D002118:Calcium