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Bestrophin‐ and TMEM16A‐associated Cl‐ conductances in rat mesenteric small arteries
Author(s) -
Matchkov Vladimir V.,
Dam Vibeke Secher,
Bødtkjer Donna,
Aalkjaer Christian
Publication year - 2013
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.27.1_supplement.913.16
Subject(s) - downregulation and upregulation , myograph , mesenteric arteries , chemistry , agonist , vascular smooth muscle , endocrinology , extracellular , niflumic acid , contraction (grammar) , vasomotion , medicine , contractility , rhoa , dids , microbiology and biotechnology , receptor , artery , biology , signal transduction , vasodilation , biochemistry , smooth muscle , gene , membrane
The presence of Ca 2+ ‐activated Cl − channels in the vascular smooth muscle cells (VSMCs) is well established, but their molecular identity is still controversial. Bestrophins and TMEM16 proteins are the most prominent candidates. We have previously characterized a cGMP‐dependent Ca 2+ ‐activated Cl − current ( I Cl(Ca) ) with unique characteristics which is present in VSMCs simultaneously with a classical I Cl(Ca) . We aimed to study the role of TMEM16A and bestrophin‐3 in the VSMC and downregulated these proteins in 2 nd order branches of rat mesenteric arteries in vivo using siRNA. Knockdown was confirmed at mRNA and protein levels 3 days after transfection. The downregulation of bestrophin‐3 induced secondary decrease in bestrophin‐1 and ‐2. The currents were validated by patch clamp and arteries were tested in isometric myograph. In contrast to bestrophin downregulation, which resulted in suppression of the cGMP dependent I Cl(Ca) , TMEM16A‐siRNA suppressed both the cGMP‐dependent and the classical I Cl(Ca) currents. Downregulation of TMEM16A or bestrophins significantly suppressed the amplitude of agonist‐induced rhythmic arterial contractions – vasomotion. The downregulation of bestrophins was without effect on agonist‐induced tonic contraction. In contrast, arteries downregulated for TMEM16A had suppressed contractility to agonist (noradrenaline and vasopressin) and extracellular K + depolarization. We conclude that both bestrophins and TMEM16A are essential for vasomotion in mesenteric small arteries but only TMEM16A is involved in agonist‐induced tonic contraction. Our results suggest modulatory interactions between these proteins at the expressional and functional levels.