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The α2 isoform Na,K‐ATPase modulates contraction of rat mesenteric small artery via cSrc‐dependent Ca 2+ sensitization
Author(s) -
Bouzinova E. V.,
Hangaard L.,
Staehr C.,
Mazur A.,
Ferreira A.,
Chibalin A. V.,
Sandow S. L.,
Xie Z.,
Aalkjaer C.,
Matchkov V. V.
Publication year - 2018
Publication title -
acta physiologica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.591
H-Index - 116
eISSN - 1748-1716
pISSN - 1748-1708
DOI - 10.1111/apha.13059
Subject(s) - ouabain , contraction (grammar) , endocrinology , vascular smooth muscle , medicine , mesenteric arteries , phosphorylation , myosin light chain kinase , muscle contraction , biology , chemistry , microbiology and biotechnology , artery , smooth muscle , sodium , organic chemistry
Aims The Na,K‐ATPase is involved in a large number of regulatory activities including cSrc‐dependent signalling. Upon inhibition of the Na,K‐ATPase with ouabain, cSrc activation is shown to occur in many cell types. This study tests the hypothesis that acute potentiation of agonist‐induced contraction by ouabain is mediated through Na,K‐ATPase‐cSrc signalling‐dependent sensitization of vascular smooth muscle cells to Ca 2+ . Methods Agonist‐induced rat mesenteric small artery contraction was examined in vitro under isometric conditions and in vivo in anaesthetized rats. Arterial wall tension and [Ca 2+ ] i in vascular smooth muscle cells were measured simultaneously. Changes in cSrc and myosin phosphatase targeting protein 1 (MYPT1) phosphorylation were analysed by Western blot. Protein expression was examined with immunohistochemistry. The α1 and α2 isoforms of the Na,K‐ATPase were transiently downregulated by siRNA transfection in vivo. Results Ten micromolar ouabain, but not digoxin, potentiated contraction to noradrenaline. This effect was not endothelium‐dependent. Ouabain sensitized smooth muscle cells to Ca 2+ , and this was associated with increased phosphorylation of cSrc and MYPT1. Inhibition of tyrosine kinase by genistein, PP2 or pNaKtide abolished the potentiating effect of ouabain on arterial contraction and Ca 2+ sensitization. Downregulation of the Na,K‐ATPase α2 isoform made arterial contraction insensitive to ouabain and tyrosine kinase inhibition. Conclusion Data suggest that micromolar ouabain potentiates agonist‐induced contraction of rat mesenteric small artery via Na,K‐ATPase‐dependent cSrc activation, which increases Ca 2+ sensitization of vascular smooth muscle cells by MYPT1 phosphorylation. This mechanism may be critical for acute control of vascular tone.