Heteromeric TRPV4/TRPC1 channels mediate calcium-sensing receptor-induced nitric oxide production and vasorelaxation in rabbit mesenteric arteries

• Published in: Vascular pharmacology 2017-09, Vol.96-98, p.53-62
• Main Authors: 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.
• Format: Article
• Language: English
• Subjects: Activation; Animals; Arteries; Blocking antibodies; Calcium; Calcium channels; Calcium oxide; Calcium Signaling; Calcium-sensing receptors; Channel gating; Chemical synthesis; Dose-Response Relationship, Drug; Endothelial cells; Endothelial Cells - drug effects; Endothelial Cells - metabolism; Endothelium; Fluorescence; Hormones; In Vitro Techniques; Ion channels; Laboratory animals; Lime; Male; Membrane Potentials; Mesenteric Artery, Superior - drug effects; Mesenteric Artery, Superior - metabolism; NG-Nitroarginine methyl ester; Nitric oxide; Nitric Oxide - metabolism; Nitric-oxide synthase; Potassium currents; Proteins; Rabbits; Receptors; Receptors, Calcium-Sensing - drug effects; Receptors, Calcium-Sensing - metabolism; TRPC Cation Channels - drug effects; TRPC Cation Channels - metabolism; TRPV Cation Channels - drug effects; TRPV Cation Channels - metabolism; Vasodilation; Vasodilation - drug effects; Vasodilator Agents - pharmacology
• ISSN: 1537-1891; 1879-3649
• DOI: 10.1016/j.vph.2017.08.005

Stimulation of calcium-sensing receptors (CaSR) by increasing the external calcium concentration (Ca2+]o) induces endothelium-dependent vasorelaxation through nitric oxide (NO) production and activation of intermediate Ca2+-activated K+ currents (IKCa) 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 [Ca2+]o 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, [Ca2+]o-evoked perforated-patch IKCa 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 IKCa channel activation in rabbit mesenteric arteries. This further implicates CaSR-induced pathways and heteromeric TRPV4-TRPC1 channels in regulating vascular tone. [Display omitted]