Orlov Sergei N, Thorin-Trescases Nathalie, Pchejetski Dimitri, Taurin Sebastien, Farhat Nada, Tremblay Johanne, Thorin Eric, Hamet Pavel
Centre de recherche, Centre hospitalier de l'Université de Montréal, Hôtel-Dieu, 3850 rue St-Urbain, Montreal, Quebec, H2W 1T7, Canada.
Pflugers Arch. 2004 Jun;448(3):335-45. doi: 10.1007/s00424-004-1262-9. Epub 2004 Apr 7.
Recent studies have demonstrated the tissue-specific effect of Na+/K+ pump inhibition by ouabain and other cardiac glycosides on cell viability. The vascular endothelium is an initial target of cardiac glycosides employed for the management of congestive heart failure as well as circulating endogenous ouabain-like substances (EOLS), the production of which is augmented in volume-expanded hypertension. This study examined the role of the Na+/K+ pump in the survival of cultured porcine aortic endothelial cells (PAEC). Complete Na+/K+ pump inhibition with ouabain led to PAEC death, indicated by cell detachment and decreased staining with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT). Based on cell swelling and resistance to benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone (z-VAD.fmk) a pan-caspase inhibitor, this type of cell death was classified as necrosis. In contrast to ouabain, Na+/K+ pump inhibition in K+-free medium did not affect PAEC viability and sharply attenuated apoptosis triggered by 3H decay-induced DNA damage. Necrosis evoked by ouabain was preserved after dissipation of the transmembrane gradient of K+ and Na+, whereas dissipation of the Na+ gradient abolished the antiapoptotic action of K+-free medium. Comparative analysis of these results and modulation of intracellular Na+ and K+ content by the above-listed stimuli showed that interaction of ouabain with Na+/K+-ATPase triggered necrosis independently of inhibition of Na+/K+ pump-mediated ion fluxes and inversion of the [Na+]i/[K+]i ratio, whereas protection against apoptosis under Na+/K+ pump inhibition in K+-depleted medium was mediated by [Na+]i elevation. The role of Na+/K+ pump-mediated regulation of endothelial cell survival and vascular remodelling seen in hypertension should be investigated further in context of EOLS and chronic treatment with digitalis.
近期研究已证实，哇巴因及其他强心苷对钠钾泵的抑制作用在不同组织中对细胞活力具有特异性影响。血管内皮是用于治疗充血性心力衰竭的强心苷以及循环内源性类哇巴因物质（EOLS）的初始作用靶点，在容量扩张性高血压中，EOLS的生成会增加。本研究探讨了钠钾泵在培养的猪主动脉内皮细胞（PAEC）存活中的作用。用哇巴因完全抑制钠钾泵会导致PAEC死亡，表现为细胞脱离以及用3 -（4,5 - 二甲基噻唑 - 2 - 基）- 2,5 - 二苯基四氮唑溴盐（MTT）染色减少。基于细胞肿胀以及对泛半胱天冬酶抑制剂苄氧羰基 - 缬氨酸 - 丙氨酸 - 天冬氨酸 - 氟甲基酮（z - VAD.fmk）的抵抗，这种细胞死亡类型被归类为坏死。与哇巴因不同，在无钾培养基中抑制钠钾泵并不影响PAEC的活力，且能显著减弱由3H衰变诱导的DNA损伤引发的细胞凋亡。哇巴因诱发的坏死在钾离子和钠离子跨膜梯度消失后仍存在，而钠离子梯度的消失则消除了无钾培养基的抗凋亡作用。对这些结果的比较分析以及上述刺激对细胞内钠离子和钾离子含量的调节表明，哇巴因与钠钾 - ATP酶的相互作用引发坏死，这与抑制钠钾泵介导的离子通量以及细胞内钠离子/钾离子比值的反转无关，而在低钾培养基中抑制钠钾泵时对细胞凋亡的保护作用是由细胞内钠离子浓度升高介导的。在EOLS和洋地黄长期治疗的背景下，钠钾泵介导的对内皮细胞存活和血管重塑的调节作用在高血压中的作用仍需进一步研究。
