1. Critical role of the α1-Na(+), K(+)-ATPase subunit in insensitivity of rodent cells to cytotoxic action of ouabain.
- Author
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Akimova OA, Tverskoi AM, Smolyaninova LV, Mongin AA, Lopina OD, La J, Dulin NO, and Orlov SN
- Subjects
- Animals, Animals, Newborn, Astrocytes metabolism, Biomarkers metabolism, Brain cytology, Cell Line, Epithelial Cells metabolism, Humans, Mice, Mitogen-Activated Protein Kinase Kinases metabolism, Muscle, Smooth cytology, Potassium metabolism, Protein Structure, Tertiary, Rats, Sprague-Dawley, Sodium metabolism, Cardiotonic Agents toxicity, Cell Death drug effects, Ouabain toxicity, Sodium-Potassium-Exchanging ATPase metabolism
- Abstract
In rodents, ubiquitous α1-Na(+), K(+)-ATPase is inhibited by ouabain and other cardiotonic steroids (CTS) at ~10(3)-fold higher concentrations than those effective in other mammals. To examine the specific roles of the CTS-sensitive α1S- and CTS-resistant α1R-Na(+), K(+)-ATPase isoforms, we compared the effects of ouabain on intracellular Na(+) and K(+) content, cell survival, and mitogen-activated protein kinases (MAPK) in human and rat vascular smooth muscle cells (HASMC and RASMC), human and rat endothelial cells (HUVEC and RAEC), and human and rat brain astrocytes. 6-h exposure of HASMC and HUVEC to 3 μM ouabain dramatically increased the intracellular [Na(+)]/[K(+)] ratio to the same extend as in RASMC and RAEC treated with 3000 μM ouabain. In 24, 3 μM ouabain triggered the death of all types of human cells used in this study. Unlike human cells, we did not detect any effect of 3000-5000 μM ouabain on the survival of rat cells, or smooth muscle cells from mouse aorta (MASMC). Unlike in the wild-type α1(R/R) mouse, ouabain triggered death of MASMC from α1(S/S) mouse expressing human α1-Na(+), K(+)-ATPase. Furthermore, transfection of HUVEC with rat α1R-Na(+), K(+)-ATPase protected them from the ouabain-induced death. In HUVEC, ouabain led to phosphorylation of p38 MAPK, whereas in RAEC it stimulated phosphorylation of ERK1/2. Overall, our results, demonstrate that the drastic differences in cytotoxic action of ouabain on human and rodent cells are caused by unique features of α1S/α1R-Na(+), K(+)-ATPase, rather than by any downstream CTS-sensitive/resistant components of the cell death machinery.
- Published
- 2015
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