Abstract Long-term study on the identification of Na,K-ATPase endogenous inhibitors in mammalian tissues has resulted in the discovery of ouabain, marinobufagenin (MBG), and other cardiotonic steroids (CTS) in the blood plasma. Production of ouabain and MBG is increased in essential hypertension and other diseases associated with hypervolemia. Here, we compared the effects of ouabain and MBG on the Na,K-ATPase activity (measured as the transport of Na + , K + , and Rb + ions) and proliferation and death of human renal epithelial cells (HRECs) and human umbilical vein endothelial cells (HUVEC) expressing α1-Na,K-ATPase. Ouabain concentration that provided the half-maximal inhibition of the Rb + influx (IC 50 ) into HRECs and HUVECs was 0.07 μM. In both types of cells, the IC 50 values for MBG were 10 times higher than for ouabain. Incubation of HREC and HUVEC with 0.001-0.01 μM ouabain for 30 h resulted in 40% increase in the [ 3 H]thymidine incorporation into DNA; further elevation of ouabain concentration to 0.1 μM completely suppressed DNA synthesis. MBG at the concentration of 0.1 μM activated DNA synthesis by 25% in HRECs, but not in HUVECs; 1 μM MBG completely inhibited DNA synthesis in HRECs and by 50% in HUVECs. In contrast to HRECs, incubation of HUVECs in the serum-free medium induced apoptosis, which was almost completely suppressed by ouabain and MBG at the concentrations of 0.1 and 3 μM, respectively. Based on these data, we can conclude that (i) the effect of MBG at the concentrations detected in the blood plasma (<0.01 μM) on HRECs and HUVECs was not due to the changes in the [Na + ] i /[K + ] i ratio; (ii) the effect of physiological concentrations of ouabain on these cells might be mediated by the activation of Na,K-ATPase, leading to cell proliferation.

中文翻译：

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哇巴因和海蟾蜍精：对人上皮和内皮细胞的生理影响

摘要 对哺乳动物组织中 Na,K-ATPase 内源性抑制剂的鉴定的长期研究导致在血浆中发现了哇巴因、海蟾蜍精 (MBG) 和其他强心类固醇 (CTS)。哇巴因和 MBG 的产生在原发性高血压和其他与血容量过多相关的疾病中增加。在这里，我们比较了哇巴因和 MBG 对 Na、K-ATPase 活性（测量为 Na + 、K + 和 Rb + 离子的转运）以及人肾上皮细胞 (HRECs) 和人脐带细胞增殖和死亡的影响。表达 α1-Na,K-ATPase 的静脉内皮细胞 (HUVEC)。提供 Rb + 流入 (IC 50 ) 进入 HREC 和 HUVEC 的半数最大抑制的哇巴因浓度为 0.07 μM。在两种类型的细胞中，MBG 的 IC 50 值比哇巴因高 10 倍。HREC 和 HUVEC 与 0.001-0.01 μM 哇巴因孵育 30 小时导致 [ 3 H] 胸苷掺入 DNA 增加 40%；哇巴因浓度进一步升高至 0.1 μM 会完全抑制 DNA 合成。0.1 μM 浓度的 MBG 在 HRECs 中激活 DNA 合成 25%，但在 HUVECs 中没有；1 μM MBG 在 HRECs 中完全抑制 DNA 合成，在 HUVECs 中抑制 50%。与 HRECs 相比，在无血清培养基中培养 HUVECs 诱导细胞凋亡，这几乎完全被浓度分别为 0.1 和 3 μM 的哇巴因和 MBG 抑制。基于这些数据，我们可以得出结论，(i) MBG 在血浆中检测到的浓度 (<0.01 μM) 对 HRECs 和 HUVECs 的影响不是由于 [Na + ] i /[K + ] i 比率；