Research Division Cardiovascular Physiology, European Center of Angioscience (ECAS), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany.
Physiology, Institute of Theoretical Medicine, Faculty of Medicine, University of Augsburg, Augsburg, Germany.
FASEB J. 2024 Sep;38(17):e70046. doi: 10.1096/fj.202400628RR.
Large-conductance, calcium-activated potassium channels (BK channels) and the Na/K-ATPase are expressed universally in vascular smooth muscle. The Na/K-ATPase may act via changes in the intracellular Ca concentration mediated by the Na/Ca exchanger (NCX) and via Src kinase. Both pathways are known to regulate BK channels. Whether BK channels functionally interact in vascular smooth muscle cells with the Na/K-ATPase remains to be elucidated. Thus, this study addressed the hypothesis that BK channels limit ouabain-induced vasocontraction. Rat mesenteric arteries were studied using isometric myography, FURA-2 fluorimetry and proximity ligation assay. The BK channel blocker iberiotoxin potentiated methoxamine-induced contractions. The cardiotonic steroid, ouabain (10 M), induced a contractile effect of IBTX at basal tension prior to methoxamine administration and enhanced the pro-contractile effect of IBTX on methoxamine-induced contractions. These facilitating effects of ouabain were prevented by the inhibition of either NCX or Src kinase. Furthermore, inhibition of NCX or Src kinase reduced the BK channel-mediated negative feedback regulation of arterial contraction. The effects of NCX and Src kinase inhibition were independent of each other. Co-localization of the Na/K-ATPase and the BK channel was evident. Our data suggest that BK channels limit ouabain-induced vasocontraction by a dual mechanism involving the NCX and Src kinase signaling. The data propose that the NCX and the Src kinase pathways, mediating the ouabain-induced activation of the BK channel, act in an independent manner.
大电导、钙激活钾通道（BK 通道）和 Na/K-ATP 酶在血管平滑肌中普遍表达。Na/K-ATP 酶可能通过 Na/Ca 交换器（NCX）介导的细胞内 Ca 浓度变化和 Src 激酶起作用。这两种途径都已知可以调节 BK 通道。BK 通道是否在血管平滑肌细胞中与 Na/K-ATP 酶具有功能性相互作用尚待阐明。因此，本研究旨在验证假设，即 BK 通道限制哇巴因诱导的血管收缩。采用等长肌描记法、FURA-2 荧光法和接近连接分析研究了大鼠肠系膜动脉。BK 通道阻断剂 Iberiotoxin 增强了甲氧胺诱导的收缩。在给予甲氧胺之前，强心甾类固醇哇巴因（10μM）在基础张力下诱导 IBTX 产生收缩作用，并增强 IBTX 对甲氧胺诱导收缩的促收缩作用。NCX 或 Src 激酶的抑制作用阻止了这些促进作用。此外，NCX 或 Src 激酶的抑制作用降低了 BK 通道对动脉收缩的负反馈调节作用。NCX 和 Src 激酶抑制的作用彼此独立。Na/K-ATP 酶和 BK 通道的共定位是明显的。我们的数据表明，BK 通道通过涉及 NCX 和 Src 激酶信号通路的双重机制限制哇巴因诱导的血管收缩。数据表明，介导哇巴因诱导的 BK 通道激活的 NCX 和 Src 激酶途径以独立的方式起作用。
