title: Activation of endothelial transient receptor potential C3 channel is required for small conductance calcium-activated potassium channel activation and sustained endothelial hyperpolarization and vasodilation of cerebral artery.
abstract: BACKGROUND
  Transient receptor potential C3 (TRPC3) has been demonstrated to be involved in the regulation of vascular tone through endothelial cell (EC) hyperpolarization and endothelium-dependent hyperpolarization-mediated vasodilation. However, the mechanism by which TRPC3 regulates these processes remains unresolved. We tested the hypothesis that endothelial receptor stimulation triggers rapid TRPC3 trafficking to the plasma membrane, where it provides the source of Ca(2+) influx for small conductance calcium-activated K(+) (SKCa) channel activation and sustained EC hyperpolarization.
  
  
  RESULTS
  Pressurized artery studies were performed with isolated mouse posterior cerebral artery. Treatment with a selective TRPC3 blocker (Pyr3) produced significant attenuation of endothelium-dependent hyperpolarization-mediated vasodilation and endothelial Ca(2+) response (EC-specific Ca(2+) biosensor) to intraluminal ATP. Pyr3 treatment also resulted in a reduced ATP-stimulated global Ca(2+) and Ca(2+) influx in primary cultures of cerebral endothelial cells. Patch-clamp studies with freshly isolated cerebral ECs demonstrated 2 components of EC hyperpolarization and K(+) current activation in response to ATP. The early phase was dependent on intermediate conductance calcium-activated K(+) channel activation, whereas the later sustained phase relied on SKC a channel activation. The SKC a channel-dependent phase was completely blocked with TRPC3 channel inhibition or in ECs of TRPC3 knockout mice and correlated with increased trafficking of TRPC3 (but not SKC a channel) to the plasma membrane.
  
  
  CONCLUSIONS
  We propose that TRPC3 dynamically regulates SKC a channel activation through receptor-dependent trafficking to the plasma membrane, where it provides the source of Ca(2+) influx for sustained SKC a channel activation, EC hyperpolarization, and endothelium-dependent hyperpolarization-mediated vasodilation.
authors.affiliation: Department of Anesthesiology, Baylor College of Medicine, Houston, TX (M.Y.K., A.B., S.P.M.).
authors.forename: Mikhail Y
authors.initials: MY
authors.lastname: Kochukov
authors.affiliation: Department of Anesthesiology, Baylor College of Medicine, Houston, TX (M.Y.K., A.B., S.P.M.).
authors.forename: Adithya
authors.initials: A
authors.lastname: Balasubramanian
authors.affiliation: Division of Intramural Research, National Institute of Environmental Health Sciences Research, Triangle Park, NC (J.A., L.B.).
authors.forename: Joel
authors.initials: J
authors.lastname: Abramowitz
authors.affiliation: Division of Intramural Research, National Institute of Environmental Health Sciences Research, Triangle Park, NC (J.A., L.B.).
authors.forename: Lutz
authors.initials: L
authors.lastname: Birnbaumer
authors.affiliation: Department of Anesthesiology, Baylor College of Medicine, Houston, TX (M.Y.K., A.B., S.P.M.) Department of Physiology and Biophysics and Graduate Program in Physiology, Cardiovascular Sciences Track, Baylor College of Medicine, Houston, TX (S.P.M.).
authors.forename: Sean P
authors.initials: SP
authors.lastname: Marrelli
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D042783:Endothelial Cells / Q000378:metabolism* / Q000502:physiology; D004730:Endothelium, Vascular; D008564:Membrane Potentials / Q000235:genetics; D051379:Mice; D018345:Mice, Knockout; D018408:Patch-Clamp Techniques; D020769:Posterior Cerebral Artery / Q000378:metabolism* / Q000502:physiology; D051640:Small-Conductance Calcium-Activated Potassium Channels / Q000378:metabolism*; D050052:TRPC Cation Channels / Q000235:genetics* / Q000378:metabolism; D014664:Vasodilation / Q000235:genetics*
chemical_list: D051640:Small-Conductance Calcium-Activated Potassium Channels; D050052:TRPC Cation Channels; C104603:TRPC3 cation channel; D002118:Calcium
keywords: cerebrovascular circulation; endothelium; endothelium‐derived factors; ion channels; vasculature