Petrushanko Irina Yu, Bogdanov Nikolai B, Lapina N, Boldyrev Alexander A, Gassmann Max, Bogdanova Anna Yu
Institute of Veterinary Physiology, Vetsuisse Faculty and Zurich Centre of Integrative Human Physiology, University of Zurich, Zurich CH-8057, Switzerland.
J Gen Physiol. 2007 Oct;130(4):389-98. doi: 10.1085/jgp.200709783.
Adjustment of the Na/K ATPase activity to changes in oxygen availability is a matter of survival for neuronal cells. We have used freshly isolated rat cerebellar granule cells to study oxygen sensitivity of the Na/K ATPase function. Along with transport and hydrolytic activity of the enzyme we have monitored alterations in free radical production, cellular reduced glutathione, and ATP levels. Both active K(+) influx and ouabain-sensitive inorganic phosphate production were maximal within the physiological pO(2) range of 3-5 kPa. Transport and hydrolytic activity of the Na/K ATPase was equally suppressed under hypoxic and hyperoxic conditions. The ATPase response to changes in oxygenation was isoform specific and limited to the alpha1-containing isozyme whereas alpha2/3-containing isozymes were oxygen insensitive. Rapid activation of the enzyme within a narrow window of oxygen concentrations did not correlate with alterations in the cellular ATP content or substantial shifts in redox potential but was completely abolished when NO production by the cells was blocked by l-NAME. Taken together our observations suggest that NO and its derivatives are involved in maintenance of high Na/K ATPase activity under physiological conditions.
将钠钾ATP酶活性调整以适应氧供应变化是神经元细胞生存的关键。我们使用新鲜分离的大鼠小脑颗粒细胞来研究钠钾ATP酶功能的氧敏感性。除了该酶的转运和水解活性外，我们还监测了自由基产生、细胞内还原型谷胱甘肽和ATP水平的变化。在3-5 kPa的生理氧分压范围内，活跃的钾离子内流和哇巴因敏感的无机磷酸盐产生均达到最大值。在缺氧和高氧条件下，钠钾ATP酶的转运和水解活性均受到同等程度的抑制。ATP酶对氧合变化的反应具有同工型特异性，仅限于含α1的同工酶，而含α2/3的同工酶对氧不敏感。在狭窄的氧浓度范围内酶的快速激活与细胞ATP含量的变化或氧化还原电位的显著变化无关，但当细胞产生的一氧化氮被L-NAME阻断时，这种激活完全被消除。综合我们的观察结果表明，一氧化氮及其衍生物在生理条件下参与维持高钠钾ATP酶活性。
