We have previously provided pharmacological evidence that stimulation of calcium-sensing receptors (CaSR) induces endothelium-dependent relaxations of rabbit mesenteric arteries through activation of heteromeric TRPV4/TRPC1 channels and nitric oxide (NO) production. The present study further investigates the role of heteromeric TRPV4/TRPC1 channels in these CaSR-induced vascular responses by comparing responses in mesenteric arteries from wild-type (WT) and TRPC1^-/- mice. In WT mice, stimulation of CaSR induced endothelium-dependent relaxations of pre-contracted tone and NO generation in endothelial cells (ECs), which were inhibited by the TRPV4 channel blocker RN1734 and the TRPC1 blocking antibody T1E3. In addition, TRPV4 and TRPC1 proteins were colocalised at, or close to, the plasma membrane of endothelial cells (ECs) from WT mice. In contrast, in TRPC1^-/- mice, CaSR-mediated vasorelaxations and NO generation were greatly reduced, unaffected by T1E3, but blocked by RN1734. In addition, the TRPV4 agonist GSK1016790A (GSK) induced endothelium-dependent vasorelaxations which were blocked by RN1734 and T1E3 in WT mice, but only by RN1734 in TRPC1^-/- mice. Moreover, GSK activated cation channel activity with a 6pS conductance in WT ECs but with a 52 pS conductance in TRPC1^-/- ECs. These results indicate that stimulation of CaSR activates heteromeric TRPV4/TRPC1 channels and NO production in ECs, which are responsible for endothelium-dependent vasorelaxations. This study also suggests that heteromeric TRPV4-TRPC1 channels may form the predominant TRPV4-containing channels in mouse mesenteric artery ECs. Together, our data further implicates CaSR-induced pathways and heteromeric TRPV4/TRPC1 channels in the regulation of vascular tone.

我们之前提供的药理学证据表明，刺激钙敏感受体 (CaSR) 通过激活异聚体 TRPV4/TRPC1 通道和一氧化氮 (NO) 产生来诱导兔肠系膜动脉的内皮依赖性舒张。本研究通过比较野生型 (WT) 和 TRPC1 在肠系膜动脉中的反应，进一步研究异聚体 TRPV4/TRPC1 通道在这些 CaSR 诱导的血管反应中的作用^-/-老鼠。在 WT 小鼠中，CaSR 的刺激可诱导内皮细胞 (EC) 中预收缩张力的内皮依赖性松弛和 NO 的产生，这被 TRPV4 通道阻断剂 RN1734 和 TRPC1 阻断抗体 T1E3 抑制。此外，TRPV4 和 TRPC1 蛋白共定位于或接近 WT 小鼠内皮细胞 (EC) 的质膜。相比之下，在 TRPC1 ^-/-小鼠中，CaSR 介导的血管舒张和 NO 生成大大减少，不受 T1E3 影响，但被 RN1734 阻断。此外，TRPV4 激动剂 GSK1016790A (GSK) 诱导内皮依赖性血管舒张，其在 WT 小鼠中被 RN1734 和 T1E3 阻断，但在 TRPC1 中仅被 RN1734 阻断^-/-老鼠。此外，GSK 激活阳离子通道活性，在 WT ECs 中具有 6pS 的电导，但在 TRPC1 ^-/- ECs 中具有 52pS 的电导。这些结果表明，CaSR 的刺激激活了 ECs 中异聚体 TRPV4/TRPC1 通道和 NO 的产生，这些通道负责内皮依赖性血管舒张。该研究还表明，异聚体 TRPV4-TRPC1 通道可能在小鼠肠系膜动脉 EC 中形成主要的含有 TRPV4 的通道。总之，我们的数据进一步表明 CaSR 诱导的途径和异聚体 TRPV4/TRPC1 通道在调节血管张力中的作用。