TRPV4 (Transient Receptor Potential Vanilloid 4) Channel-Dependent Negative Feedback Mechanism Regulates Gq Protein-Coupled Receptor-Induced Vasoconstriction

Arterioscler Thromb Vasc Biol. 2018 Mar;38(3):542-554. doi: 10.1161/ATVBAHA.117.310038. Epub 2018 Jan 4.

Abstract

Objective: Several physiological stimuli activate smooth muscle cell (SMC) GqPCRs (Gq protein-coupled receptors) to cause vasoconstriction. As a protective mechanism against excessive vasoconstriction, SMC GqPCR stimulation invokes endothelial cell vasodilatory signaling. Whether Ca2+ influx in endothelial cells contributes to the regulation of GqPCR-induced vasoconstriction remains unknown. Ca2+ influx through TRPV4 (transient receptor potential vanilloid 4) channels is a key regulator of endothelium-dependent vasodilation. We hypothesized that SMC GqPCR stimulation engages endothelial TRPV4 channels to limit vasoconstriction.

Approach and results: Using high-speed confocal microscopy to record unitary Ca2+ influx events through TRPV4 channels (TRPV4 sparklets), we report that activation of SMC α1ARs (alpha1-adrenergic receptors) with phenylephrine or thromboxane A2 receptors with U46619 stimulated TRPV4 sparklets in the native endothelium from mesenteric arteries. Activation of endothelial TRPV4 channels did not require an increase in Ca2+ as indicated by the lack of effect of L-type Ca2+ channel activator or chelator of intracellular Ca2+ EGTA-AM. However, gap junction communication between SMCs and endothelial cells was required for phenylephrine activation or U46619 activation of endothelial TRPV4 channels. Lowering inositol 1,4,5-trisphosphate levels with phospholipase C inhibitor or lithium chloride suppressed phenylephrine activation of endothelial TRPV4 sparklets. Moreover, uncaging inositol 1,4,5-trisphosphate profoundly increased TRPV4 sparklet activity. In pressurized arteries, phenylephrine-induced vasoconstriction was followed by a slow, TRPV4-dependent vasodilation, reflecting activation of negative regulatory mechanism. Consistent with these data, phenylephrine induced a significantly higher increase in blood pressure in TRPV4-/- mice.

Conclusions: These results demonstrate that SMC GqPCR stimulation triggers inositol 1,4,5-trisphosphate-dependent activation of endothelial TRPV4 channels to limit vasoconstriction.

Keywords: TRPV cation channel; endothelial cells; gap junctions; heterocellular communication; vasoconstriction.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adrenergic alpha-1 Receptor Agonists / pharmacology
  • Animals
  • Biosensing Techniques
  • Blood Pressure
  • Calcium / metabolism*
  • Calcium Signaling* / drug effects
  • Calmodulin / genetics
  • Calmodulin / metabolism
  • Cell Communication
  • Endothelium, Vascular / drug effects
  • Endothelium, Vascular / metabolism*
  • Feedback, Physiological
  • Green Fluorescent Proteins / genetics
  • Green Fluorescent Proteins / metabolism
  • Inositol 1,4,5-Trisphosphate / metabolism
  • Kinetics
  • Male
  • Mesenteric Arteries / metabolism
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Muscle, Smooth, Vascular / drug effects
  • Muscle, Smooth, Vascular / metabolism*
  • Receptors, Adrenergic, alpha-1 / drug effects
  • Receptors, Adrenergic, alpha-1 / metabolism*
  • Receptors, Thromboxane A2, Prostaglandin H2 / agonists
  • Receptors, Thromboxane A2, Prostaglandin H2 / metabolism*
  • TRPV Cation Channels / deficiency
  • TRPV Cation Channels / genetics
  • TRPV Cation Channels / metabolism*
  • Type C Phospholipases / metabolism
  • Vasoconstriction* / drug effects
  • Vasodilation

Substances

  • Adrenergic alpha-1 Receptor Agonists
  • Calmodulin
  • Receptors, Adrenergic, alpha-1
  • Receptors, Thromboxane A2, Prostaglandin H2
  • TRPV Cation Channels
  • Trpv4 protein, mouse
  • enhanced green fluorescent protein
  • Green Fluorescent Proteins
  • Inositol 1,4,5-Trisphosphate
  • Type C Phospholipases
  • Calcium