title: K(V)7.4 channels participate in the control of rodent renal vascular resting tone.
abstract: OBJECTIVE
  We tested the hypothesis that K(V)7 channels contribute to basal renal vascular tone and that they participate in agonist-induced renal vasoconstriction or vasodilation.
  
  
  METHODS
  KV 7 channel subtypes in renal arterioles were characterized by immunofluorescence. Renal blood flow (RBF) was measured using an ultrasonic flow probe. The isometric tension of rat interlobar arteries was examined in a wire myograph. Mice afferent arteriolar diameter was assessed utilizing the perfused juxtamedullary nephron technique.
  
  
  RESULTS
  Immunofluorescence revealed that K(V)7.4 channels were expressed in rat afferent arterioles. The K(V)7 blocker XE991 dose-dependently increased the isometric tension of rat interlobar arteries and caused a small (approx. 4.5%) RBF reduction in vivo. Nifedipine abolished these effects. Likewise, XE991 reduced mouse afferent arteriolar diameter by approx. 5%. The K(V)7.2-5 stimulator flupirtine dose-dependently relaxed isolated rat interlobar arteries and increased (approx. 5%) RBF in vivo. The RBF responses to NE or Ang II administration were not affected by pre-treatment with XE991 or flupirtine. XE991 pre-treatment caused a minor augmentation of the acetylcholine-induced increase in RBF, while flupirtine pre-treatment did not affect this response.
  
  
  CONCLUSIONS
  It is concluded that K(V)7 channels, via nifedipine sensitive channels, have a role in the regulation of basal renal vascular tone. There is no indication that K(V)7 channels have an effect on agonist-induced renal vasoconstriction while there is a small effect on acetylcholine-induced vasodilation.
authors.affiliation: Division of Renal and Vascular Physiology, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: M
authors.initials: M
authors.lastname: Salomonsson
authors.affiliation: Division of Renal and Vascular Physiology, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark.|Biomedical Engineering, Department of Electrical Engineering, Technical University of Denmark, Lyngby, Denmark.
authors.forename: J C
authors.initials: JC
authors.lastname: Brasen
authors.affiliation: Danish National Research Foundation Center for Cardiac Arrhythmia, University of Copenhagen, Copenhagen, Denmark.
authors.forename: T H
authors.initials: TH
authors.lastname: Braunstein
authors.affiliation: Division of Renal and Vascular Physiology, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: P
authors.initials: P
authors.lastname: Hagelqvist
authors.affiliation: Division of Renal and Vascular Physiology, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark.|Danish National Research Foundation Center for Cardiac Arrhythmia, University of Copenhagen, Copenhagen, Denmark.
authors.forename: N-H
authors.initials: NH
authors.lastname: Holstein-Rathlou
authors.affiliation: Division of Renal and Vascular Physiology, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: C M
authors.initials: CM
authors.lastname: Sorensen
mesh_terms: D000818:Animals; D001783:Blood Flow Velocity / Q000502:physiology*; D015640:Ion Channel Gating / Q000502:physiology; D051656:KCNQ Potassium Channels / Q000502:physiology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D017207:Rats, Sprague-Dawley; D012077:Renal Artery / Q000502:physiology*; D012079:Renal Circulation / Q000502:physiology*; D012146:Rest / Q000502:physiology; D014655:Vascular Resistance / Q000502:physiology*
chemical_list: D051656:KCNQ Potassium Channels; C492167:Kcnq4 protein, mouse; C492166:Kcnq4 protein, rat
keywords: KCNQ; afferent arteriole; hyperpolarization; renal hemodynamics; renal vascular resistance