title: Role of Na+-K+-2Cl- Cotransporter 1 in Phenylephrine-Induced Rhythmic Contraction in the Mouse Aorta: Regulation of Na+-K+-2Cl- Cotransporter 1 by Ca2+ Sparks and KCa Channels.
abstract: OBJECTIVE
  Vasoconstrictor-induced rhythmic contraction of arteries or veins has been observed both in vivo and in vitro. Many studies have reported that gap junctions, ryanodine receptors, Na+, K+-ATPase and other factors are involved in vasoconstrictor-induced rhythmic contraction in vascular smooth muscle. However, the mechanism is still not completely understood.
  
  
  METHODS
  We used vessel tension measurements, intracellular recordings and intracellular Cl- concentration ([Cl-]i) measurements to investigate the mechanism underlying phenylephrine (PE)-induced rhythmic contraction in the mouse aorta.
  
  
  RESULTS
  We found that Na+-K+-2Cl- cotransporter 1 (NKCC1) inhibitor bumetanide abolished PE-induced rhythmic contraction. The Cl- channel blockers DIDS and niflumic acid initially augmented the amplitude of PE-induced rhythmic contraction but later inhibited the rhythmic contraction. The large Ca2+-activated K+ channel blocker TEA and iberiotoxin increased the amplitude of PE-induced rhythmic contraction. The voltage-dependent Ca2+ channel blocker, nifedipine, and a Ca2+-free solution abolished PE-induced rhythmic contraction. The inhibitor of ryanodine receptors in the sarcoplasmic reticulum, ryanodine, inhibited PE-induced rhythmic contraction. Moreover, bumetanide hyperpolarized the membrane potential of vascular smooth muscle cells in a resting state or after PE pre-treatment. Bumetanide, niflumic acid, ryanodine, iberiotoxin, nifedipine and Ca2+-free buffer significantly suppressed the PE-induced [Cl-]i increase.
  
  
  CONCLUSIONS
  These data indicate that NKCC1 is involved in the formation of PE-induced rhythmic contraction, and we also provide a method with which to indirectly observe the NKCC1 activity in isolated intact mouse thoracic aortas.
authors.affiliation: Department of Physiology, Anhui Medical University, Hefei, Anhui, China.
authors.forename: Bing
authors.initials: B
authors.lastname: Shen
authors.forename: Jie
authors.initials: J
authors.lastname: Fu
authors.forename: Jizheng
authors.initials: J
authors.lastname: Guo
authors.forename: Jie
authors.initials: J
authors.lastname: Zhang
authors.forename: Xia
authors.initials: X
authors.lastname: Wang
authors.forename: Xiang
authors.initials: X
authors.lastname: Pan
authors.forename: Meihua
authors.initials: M
authors.lastname: Chen
authors.forename: Yifan
authors.initials: Y
authors.lastname: Zhou
authors.forename: Min
authors.initials: M
authors.lastname: Zhu
authors.forename: Juan
authors.initials: J
authors.lastname: Du
mesh_terms: D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects* / Q000378:metabolism; D002034:Bumetanide / Q000494:pharmacology; D020013:Calcium Signaling / Q000187:drug effects*; D005260:Female; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D051379:Mice; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism; D010656:Phenylephrine / Q000494:pharmacology*; D024681:Potassium Channels, Calcium-Activated / Q000187:drug effects; D064506:Solute Carrier Family 12, Member 2 / Q000378:metabolism*; D014662:Vasoconstrictor Agents / Q000494:pharmacology*
chemical_list: D024681:Potassium Channels, Calcium-Activated; C578878:Slc12a2 protein, mouse; D064506:Solute Carrier Family 12, Member 2; D014662:Vasoconstrictor Agents; D002034:Bumetanide; D010656:Phenylephrine