Tverskoi A M, Sidorenko S V, Klimanova E A, Akimova O A, Smolyaninova L V, Lopina O D, Orlov S N
Lomonosov Moscow State University, Faculty of Biology, Moscow, 119991, Russia.
Biochemistry (Mosc). 2016 Aug;81(8):876-83. doi: 10.1134/S0006297916080083.
Side-by-side with inhibition of the Na+,K+-ATPase ouabain and other cardiotonic steroids (CTS) can affect cell functions by mechanisms other than regulation of the intracellular Na+ and K+ ratio ([Na+]i/[K+]i). Thus, we compared the dose- and time-dependences of the effect of ouabain on intracellular [Na+]i/[K+]i ratio, Na+,K+-ATPase activity, and proliferation of human umbilical vein endothelial cells (HUVEC). Treatment of the cells with 1-3 nM ouabain for 24-72 h decreased the [Na+]i/[K+]i ratio and increased cell proliferation by 20-50%. We discovered that the same ouabain concentrations increased Na+,K+-ATPase activity by 25-30%, as measured by the rate of (86)Rb(+) influx. Higher ouabain concentrations inhibited Na+,K+-ATPase, increased [Na+]i/[K+]i ratio, suppressed cell growth, and caused cell death. When cells were treated with low ouabain concentrations for 48 or 72 h, a negative correlation between [Na+]i/[K+]i ratio and cell growth activation was observed. In cells treated with high ouabain concentrations for 24 h, the [Na+]i/[K+]i ratio correlated positively with proliferation inhibition. These data demonstrate that inhibition of HUVEC proliferation at high CTS concentrations correlates with dissipation of the Na+ and K+ concentration gradients, whereas cell growth stimulation by low CTS doses results from activation of Na+,K+-ATPase and decrease in the [Na+]i/[K+]i ratio.
与抑制钠钾ATP酶同时，哇巴因和其他强心甾体（CTS）可通过调节细胞内钠钾比率（[Na⁺]i/[K⁺]i）以外的机制影响细胞功能。因此，我们比较了哇巴因对人脐静脉内皮细胞（HUVEC）细胞内[Na⁺]i/[K⁺]i比率、钠钾ATP酶活性和增殖作用的剂量和时间依赖性。用1 - 3 nM哇巴因处理细胞24 - 72小时可降低[Na⁺]i/[K⁺]i比率，并使细胞增殖增加20 - 50%。我们发现，相同浓度的哇巴因可使钠钾ATP酶活性增加25 - 30%，这通过⁸⁶Rb⁺内流速率来测定。更高浓度的哇巴因会抑制钠钾ATP酶，增加[Na⁺]i/[K⁺]i比率，抑制细胞生长并导致细胞死亡。当用低浓度哇巴因处理细胞48或72小时时，观察到[Na⁺]i/[K⁺]i比率与细胞生长激活之间呈负相关。在用高浓度哇巴因处理细胞24小时时，[Na⁺]i/[K⁺]i比率与增殖抑制呈正相关。这些数据表明，高浓度CTS抑制HUVEC增殖与钠钾浓度梯度的消散相关，而低剂量CTS刺激细胞生长是由于钠钾ATP酶的激活和[Na⁺]i/[K⁺]i比率的降低。
