Vascular Kv7 channels control intracellular Ca2+ dynamics in smooth muscle

Yuan-Ming Tsai, Frederick Jones, Pierce Mullen, Karen E Porter, Derek Steele, Chris Peers, Nikita Gamper

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)


Voltage-gated Kv7 (or KCNQ) channels control activity of excitable cells, including vascular smooth muscle cells (VSMCs), by setting their resting membrane potential and controlling other excitability parameters. Excitation-contraction coupling in muscle cells is mediated by Ca2+ but until now, the exact role of Kv7 channels in cytosolic Ca2+ dynamics in VSMCs has not been fully elucidated. We utilised microfluorimetry to investigate the impact of Kv7 channel activity on intracellular Ca2+ levels and electrical activity of rat A7r5 VSMCs and primary human internal mammary artery (IMA) SMCs. Both, direct (XE991) and G protein coupled receptor mediated (vasopressin, AVP) Kv7 channel inhibition induced robust Ca2+ oscillations, which were significantly reduced in the presence of Kv7 channel activator, retigabine, L-type Ca2+ channel inhibitor, nifedipine, or T-type Ca2+ channel inhibitor, NNC 55-0396, in A7r5 cells. Membrane potential measured using FluoVolt exhibited a slow depolarisation followed by a burst of sharp spikes in response to XE991; spikes were temporally correlated with Ca2+ oscillations. Phospholipase C inhibitor (edelfosine) reduced AVP-induced, but not XE991-induced Ca2+ oscillations. AVP and XE991 induced a large increase of [Ca2+]i in human IMA, which was also attenuated with retigabine, nifedipine and NNC 55-0396. RT-PCR, immunohistochemistry and electrophysiology suggested that Kv7.5 was the predominant Kv7 subunit in both rat and human arterial SMCs; CACNA1C (Cav1.2; L-type) and CACNA1 G (Cav3.1; T-type) were the most abundant voltage-gated Ca2+ channel gene transcripts in both types of VSMCs. This study establishes Kv7 channels as key regulators of Ca2+ signalling in VSMCs with Kv7.5 playing a dominant role.

Original languageEnglish
Pages (from-to)102283
JournalCell Calcium
Publication statusPublished - Dec 2020


  • Animals
  • Calcium/metabolism
  • Calcium Channel Blockers/pharmacology
  • Calcium Channels/metabolism
  • Calcium Signaling/drug effects
  • Cells, Cultured
  • Endoplasmic Reticulum/drug effects
  • Gene Expression Regulation/drug effects
  • HEK293 Cells
  • Humans
  • Intracellular Space/metabolism
  • KCNQ Potassium Channels/genetics
  • Mammary Arteries/cytology
  • Muscle, Smooth, Vascular/drug effects
  • Rats
  • Type C Phospholipases/metabolism
  • Vasopressins/pharmacology


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