title: Sensory nerves and transient receptor potential vanilloid 1 channels in CO(2) regulation of cerebrovascular tone.
abstract: This study investigated the involvement of sensory nerves and, in particular, neuronal transient receptor potential vanilloid (TRPV) 1 channels, in the CO(2)-mediated regulation of cerebrovascular tone. Basilar artery diameter and blood flow velocity in the ventral midbrain were determined in a rat cranial window preparation by digital imaging and laser-Doppler flowmetry, respectively. Superfusion of the basilar artery with capsaicin, a selective TRPV1 receptor agonist, caused a transient relaxation, consistent with acute desensitization of neuronal TRPV1 channels. Constriction to respiratory hypocapnia remained unaffected following capsaicin superfusion. Denervation of sensory nerves by repeated capsaicin injection of neonates also did not reduce the respiratory hypocapnia constriction of the basilar artery as well as the decreased flow velocity in the ventral midbrain in adults. These findings suggest that sensory nerves and, in particular, neuronal TRPV1 channels, do not play a role in respiratory hypocapnia constriction and decreased flow, at least in rat basilar artery and ventral midbrain.
authors.affiliation: Research Service, Veterans Affairs Medical Center, Department of Pharmacology and Cell Biophysics, University of Cincinnati College of Medicine, PO Box 670575, Cincinnati, OH 45267-0575, USA.
authors.forename: SeongHun
authors.initials: S
authors.lastname: Yoon
authors.affiliation: Surgical Service, Veterans Affairs Medical Center, The Neuroscience Institute: Department of Neurosurgery, University of Cincinnati College of Medicine, PO Box 670515, Cincinnati, OH 45267-0515, USA.
authors.forename: Mario
authors.initials: M
authors.lastname: Zuccarello
authors.affiliation: Research Service, Veterans Affairs Medical Center, Department of Pharmacology and Cell Biophysics, University of Cincinnati College of Medicine, PO Box 670575, Cincinnati, OH 45267-0575, USA. Electronic address: Robert.Rapoport@uc.edu.
authors.forename: Robert M
authors.initials: RM
authors.lastname: Rapoport
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001488:Basilar Artery / Q000187:drug effects / Q000254:growth & development / Q000502:physiology*; D001783:Blood Flow Velocity / Q000502:physiology; D002211:Capsaicin / Q000494:pharmacology; D002245:Carbon Dioxide / Q000378:metabolism*; D002560:Cerebrovascular Circulation / Q000187:drug effects / Q000502:physiology; D016857:Hypocapnia / Q000503:physiopathology; D017078:Laser-Doppler Flowmetry; D008636:Mesencephalon / Q000098:blood supply* / Q000187:drug effects / Q000254:growth & development / Q000502:physiology*; D009126:Muscle Relaxation / Q000187:drug effects / Q000502:physiology; D051381:Rats; D011984:Sensory Receptor Cells / Q000187:drug effects / Q000502:physiology*; D018689:Sensory System Agents / Q000494:pharmacology; D050916:TRPV Cation Channels / Q000037:antagonists & inhibitors / Q000378:metabolism*
chemical_list: D018689:Sensory System Agents; D050916:TRPV Cation Channels; C494484:TRPV1 receptor; D002245:Carbon Dioxide; D002211:Capsaicin
keywords: Cerebrovascular tone; Respiratory hypocapnia; Sensory nerves; TRPV1 channels