Greenberg Harry Z E, Carlton-Carew Simonette R E, Khan Dhanak M, Zargaran Alexander K, Jahan Kazi S, Vanessa Ho W-S, Albert Anthony P
Vascular Biology Research Centre, Molecular & Clinical Sciences Research Institute, St. George's, University of London, Cranmer Terrace, London SW17 0RE, UK.
Vascular Biology Research Centre, Molecular & Clinical Sciences Research Institute, St. George's, University of London, Cranmer Terrace, London SW17 0RE, UK.
Vascul Pharmacol. 2017 Sep;96-98:53-62. doi: 10.1016/j.vph.2017.08.005. Epub 2017 Sep 1.
Stimulation of calcium-sensing receptors (CaSR) by increasing the external calcium concentration (Ca]) induces endothelium-dependent vasorelaxation through nitric oxide (NO) production and activation of intermediate Ca-activated K currents (IK) channels in rabbit mesenteric arteries. The present study investigates the potential role of heteromeric TRPV4-TRPC1 channels in mediating these CaSR-induced vascular responses. Immunocytochemical and proximity ligation assays showed that TRPV4 and TRPC1 proteins were expressed and co-localised at the plasma membrane of freshly isolated endothelial cells (ECs). In wire myography studies, increasing [Ca] between 1 and 6mM induced concentration-dependent relaxations of methoxamine (MO)-induced pre-contracted tone, which were inhibited by the TRPV4 antagonists RN1734 and HC067047, and the externally-acting TRPC1 blocking antibody T1E3. In addition, CaSR-evoked NO production in ECs measured using the fluorescent NO indicator DAF-FM was reduced by RN1734 and T1E3. In contrast, [Ca]-evoked perforated-patch IK currents in ECs were unaffected by RN1734 and T1E3. The TRPV4 agonist GSK1016790A (GSK) induced endothelium-dependent relaxation of MO-evoked pre-contracted tone and increased NO production, which were inhibited by the NO synthase inhibitor L-NAME, RN1734 and T1E3. GSK activated 6pS cation channel activity in cell-attached patches from ECs which was blocked by RN1734 and T1E3. These findings indicate that heteromeric TRPV4-TRPC1 channels mediate CaSR-induced vasorelaxation through NO production but not IK channel activation in rabbit mesenteric arteries. This further implicates CaSR-induced pathways and heteromeric TRPV4-TRPC1 channels in regulating vascular tone.
通过提高细胞外钙浓度（Ca]）刺激钙敏感受体（CaSR），可通过产生一氧化氮（NO）和激活家兔肠系膜动脉中的中间钙激活钾电流（IK）通道，诱导内皮依赖性血管舒张。本研究探讨了异源三聚体TRPV4 - TRPC1通道在介导这些CaSR诱导的血管反应中的潜在作用。免疫细胞化学和邻近连接分析表明，TRPV4和TRPC1蛋白在新鲜分离的内皮细胞（ECs）的质膜上表达并共定位。在血管张力测定研究中，将[Ca]在1至6 mM之间增加，可诱导甲氧明（MO）诱导的预收缩张力浓度依赖性舒张，这被TRPV4拮抗剂RN1734和HC067047以及外源性TRPC1阻断抗体T1E3所抑制。此外，使用荧光NO指示剂DAF - FM测量的ECs中CaSR诱发的NO产生被RN1734和T1E3降低。相比之下，[Ca]诱发的ECs穿孔膜片IK电流不受RN1734和T1E3影响。TRPV4激动剂GSK1016790A（GSK）诱导MO诱发的预收缩张力的内皮依赖性舒张并增加NO产生，这被NO合酶抑制剂L - NAME、RN1734和T1E3所抑制。GSK激活了ECs细胞贴附膜片中的6pS阳离子通道活性，该活性被RN1734和T1E3阻断。这些发现表明，异源三聚体TRPV4 - TRPC1通道通过产生NO而非激活IK通道来介导CaSR诱导的家兔肠系膜动脉血管舒张。这进一步表明CaSR诱导的途径和异源三聚体TRPV4 - TRPC1通道参与调节血管张力。
