title: Localized TRPA1 channel Ca2+ signals stimulated by reactive oxygen species promote cerebral artery dilation.
abstract: Reactive oxygen species (ROS) can have divergent effects in cerebral and peripheral circulations. We found that Ca(2+)-permeable transient receptor potential ankyrin 1 (TRPA1) channels were present and colocalized with NADPH (reduced form of nicotinamide adenine dinucleotide phosphate) oxidase 2 (NOX2), a major source of ROS, in the endothelium of cerebral arteries but not in other vascular beds. We recorded and characterized ROS-triggered Ca(2+) signals representing Ca(2+) influx through single TRPA1 channels, which we called "TRPA1 sparklets." TRPA1 sparklet activity was low under basal conditions but was stimulated by NOX-generated ROS. Ca(2+) entry during a single TRPA1 sparklet was twice that of a TRPV4 sparklet and ~200 times that of an L-type Ca(2+) channel sparklet. TRPA1 sparklets representing the simultaneous opening of two TRPA1 channels were more common in endothelial cells than in human embryonic kidney (HEK) 293 cells expressing TRPA1. The NOX-induced TRPA1 sparklets activated intermediate-conductance, Ca(2+)-sensitive K(+) channels, resulting in smooth muscle hyperpolarization and vasodilation. NOX-induced activation of TRPA1 sparklets and vasodilation required generation of hydrogen peroxide and lipid-peroxidizing hydroxyl radicals as intermediates. 4-Hydroxy-nonenal, a metabolite of lipid peroxidation, also increased TRPA1 sparklet frequency and dilated cerebral arteries. These data suggest that in the cerebral circulation, lipid peroxidation metabolites generated by ROS activate Ca(2+) influx through TRPA1 channels in the endothelium of cerebral arteries to cause dilation.
authors.affiliation: Vascular Physiology Research Group, Department of Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA.
authors.forename: Michelle N
authors.initials: MN
authors.lastname: Sullivan
authors.affiliation: Department of Pharmacology, University of Vermont School of Medicine, Burlington, VT 05405, USA.
authors.forename: Albert L
authors.initials: AL
authors.lastname: Gonzales
authors.affiliation: Department of Pharmacology, University of Nevada School of Medicine, Reno, NV 89557-0318, USA.
authors.forename: Paulo W
authors.initials: PW
authors.lastname: Pires
authors.affiliation: Vascular Physiology Research Group, Department of Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA.
authors.forename: Allison
authors.initials: A
authors.lastname: Bruhl
authors.affiliation: Department of Physiology, University of Tennessee Health Science Center, Memphis, TN 38163, USA.
authors.forename: M Dennis
authors.initials: MD
authors.lastname: Leo
authors.affiliation: Vascular Physiology Research Group, Department of Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA.
authors.forename: Wencheng
authors.initials: W
authors.lastname: Li
authors.affiliation: Department of Pharmacology, University of Nevada School of Medicine, Reno, NV 89557-0318, USA.
authors.forename: Agathe
authors.initials: A
authors.lastname: Oulidi
authors.affiliation: Department of Neurosurgery, University of Tennessee Health Science Center, Memphis, TN 38163, USA.
authors.forename: Frederick A
authors.initials: FA
authors.lastname: Boop
authors.affiliation: Vascular Physiology Research Group, Department of Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA.
authors.forename: Yumei
authors.initials: Y
authors.lastname: Feng
authors.affiliation: Department of Physiology, University of Tennessee Health Science Center, Memphis, TN 38163, USA.
authors.forename: Jonathan H
authors.initials: JH
authors.lastname: Jaggar
authors.affiliation: Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta T2N 4N1, Canada.
authors.forename: Donald G
authors.initials: DG
authors.lastname: Welsh
authors.affiliation: Department of Pharmacology, University of Nevada School of Medicine, Reno, NV 89557-0318, USA. searley@medicine.nevada.edu.
authors.forename: Scott
authors.initials: S
authors.lastname: Earley
mesh_terms: D000447:Aldehydes / Q000378:metabolism; D000818:Animals; D015153:Blotting, Western; D015220:Calcium Channels / Q000235:genetics / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology*; D002536:Cerebral Arteries / Q000187:drug effects / Q000502:physiology*; D057809:HEK293 Cells; D006801:Humans; D007150:Immunohistochemistry; D047468:Immunoprecipitation; D015227:Lipid Peroxidation / Q000502:physiology; D008562:Membrane Glycoproteins / Q000378:metabolism; D008564:Membrane Potentials / Q000502:physiology; D051379:Mice; D018345:Mice, Knockout; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism / Q000494:pharmacology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D000074025:TRPA1 Cation Channel; D050051:Transient Receptor Potential Channels / Q000235:genetics / Q000378:metabolism*; D014664:Vasodilation / Q000187:drug effects* / Q000502:physiology
chemical_list: D000447:Aldehydes; D015220:Calcium Channels; D008562:Membrane Glycoproteins; D009419:Nerve Tissue Proteins; D017382:Reactive Oxygen Species; D000074025:TRPA1 Cation Channel; C473350:TRPA1 protein, human; D050051:Transient Receptor Potential Channels; C056558:CYBB protein, human; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases; C027576:4-hydroxy-2-nonenal