Purpose: The mechanism of cardioprotection by Kv7.1– 5 (KCNQ1-5) channels inhibition by XE991 is unclear. We examined the impact of administration time on the cardioprotective efficacy of XE991, the involvement of key pro-survival kinases, and the importance of the Kv7 subchannels.
Methods: Isolated perfused rat hearts were divided into five groups: 1) vehicle, 2) pre-, 3) post- or 4) pre- and post-ischemic administration of XE991 or 5) chromanol 293B (Kv7.1 inhibitor) followed by infarct size quantification. HL-1 cells undergoing simulated ischemia/reperfusion were exposed to either a) vehicle, b) pre-, c) per-, d) post-ischemic administration of XE991 or pre-, per- and post-ischemic administration of e) XE991, f) Chromanol 293B or g) HMR1556 (Kv7.1 inhibitor). HL-1 cell injury was evaluated by propidium iodide/Hoechst staining. Pro-survival kinase activation of Akt, Erk and STAT3 in XE991-mediated HL-1 cell protection was evaluated using phosphokinase inhibitors. Kv7 subtype expression was examined by RT-PCR and qPCR.
Results: XE991, but not Chromanol 293B, reduced infarct size and improved hemodynamic recovery in all isolated heart groups. XE991 protected HL-1 cells when administered during simulated ischemia. Minor activation of the survival kinases was observed in cells exposed to XE991 but pharmacological inhibition of kinase activation did not reduce XE991-mediated protection. Kv7 subchannels 1– 5 were all present in rat hearts but predominately Kv7.1 and Kv7.4 were present in HL-1 cells and selective Kv7.1 did not reduce ischemia/reperfusion injury.
Conclusion: The cardioprotective efficacy of XE991 seems to depend on its presence during ischemia and early reperfusion and do not rely on RISK (p-Akt and p-Erk) and SAFE (p-STAT3) pathway activation. The protective effect of XE991 seems mainly mediated through the Kv7.4 subchannel.

Keywords: cardioprotection, Kv7 channels, myocardial ischemia reperfusion injury, myocardial infarction


中文翻译：

---

给药时间和 Kv7 亚通道对 Kv7 通道抑制的心脏保护功效的影响。

目的： XE991 对 Kv7.1–5 (KCNQ1-5) 通道抑制的心脏保护机制尚不清楚。我们检查了给药时间对 XE991 的心脏保护功效的影响、关键促存活激酶的参与以及 Kv7 子通道的重要性。
方法：将分离的灌注大鼠心脏分为五组：1) 载体，2) 前，3) 后或 4) XE991 或 5) chromanol 293B（Kv7.1 抑制剂）的缺血前和缺血后给药，然后是梗死面积量化。将经历模拟缺血/再灌注的 HL-1 细胞暴露于 a) 载体、b) 前、c) 后、d) XE991 的缺血后给药或 e) XE991 的前、缺血后和缺血后给药, f) Chromanol 293B 或 g) HMR1556 (Kv7.1 抑制剂)。通过碘化丙啶/赫斯特染色评估 HL-1 细胞损伤。使用磷酸激酶抑制剂评估了 XE991 介导的 HL-1 细胞保护中 Akt、Erk 和 STAT3 的促存活激酶活化。通过 RT-PCR 和 qPCR 检查 Kv7 亚型表达。
结果：XE991，但不是 Chromanol 293B，在所有离体心脏组中减少了梗塞面积并改善了血流动力学恢复。XE991 在模拟缺血期间给药时可保护 HL-1 细胞。在暴露于 XE991 的细胞中观察到存活激酶的轻微活化，但激酶活化的药理学抑制并未降低 XE991 介导的保护作用。Kv7 亚通道 1-5 都存在于大鼠心脏中，但主要存在于 HL-1 细胞中的 Kv7.1 和 Kv7.4 并且选择性 Kv7.1 不会减少缺血/再灌注损伤。
结论：XE991 的心脏保护功效似乎取决于它在缺血和早期再灌注期间的存在，而不依赖于 RISK（p-Akt 和 p-Erk）和 SAFE（p-STAT3）通路的激活。XE991 的保护作用似乎主要通过 Kv7.4 子通道介导。

关键词：心脏保护，Kv7通道，心肌缺血再灌注损伤，心肌梗死