title: Plasma membrane stretch activates transient receptor potential vanilloid and ankyrin channels in Merkel cells from hamster buccal mucosa.
abstract: Merkel cells (MCs) have been proposed to form a part of the MC-neurite complex with sensory neurons. Many transient receptor potential (TRP) channels have been identified in mammals; however, the activation properties of these channels in oral mucosal MCs remain to be clarified. We investigated the biophysical and pharmacological properties of TRP vanilloid (TRPV)-1, TRPV2, TRPV4, TRP ankyrin (TRPA)-1, and TRP melastatin (TRPM)-8 channels, which are sensitive to osmotic and mechanical stimuli by measurement of intracellular free Ca(2+) concentration ([Ca(2+)]i) using fura-2. We also analyzed their localization patterns through immunofluorescence. MCs showed immunoreaction for TRPV1, TRPV2, TRPV4, TRPA1, and TRPM8 channels. In the presence of extracellular Ca(2+), the hypotonic test solution evoked Ca(2+) influx. The [Ca(2+)]i increases were inhibited by TRPV1, TRPV2, TRPV4, or TRPA1 channel antagonists, but not by the TRPM8 channel antagonist. Application of TRPV1, TRPV2, TRPV4, TRPA1, or TRPM8 channel selective agonists elicited transient increases in [Ca(2+)]i only in the presence of extracellular Ca(2+). The results indicate that membrane stretching in MCs activates TRPV1, TRPV2, TRPV4, and TRPA1 channels, that it may be involved in synaptic transmission to sensory neurons, and that MCs could contribute to the mechanosensory transduction sequence.
authors.affiliation: Department of Dental Anesthesiology, Tokyo Dental College, Chiba 261-8502, Japan.
authors.forename: Manabu
authors.initials: M
authors.lastname: Soya
authors.affiliation: Department of Physiology, Tokyo Dental College, Tokyo 101-0061, Japan.
authors.forename: Masaki
authors.initials: M
authors.lastname: Sato
authors.affiliation: Department of Physiology, Tokyo Dental College, Tokyo 101-0061, Japan.
authors.forename: Ubaidus
authors.initials: U
authors.lastname: Sobhan
authors.affiliation: Department of Physiology, Tokyo Dental College, Tokyo 101-0061, Japan.
authors.forename: Maki
authors.initials: M
authors.lastname: Tsumura
authors.affiliation: Department of Dental Anesthesiology, Tokyo Dental College, Chiba 261-8502, Japan.
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Ichinohe
authors.affiliation: Department of Physiology, Tokyo Dental College, Tokyo 101-0061, Japan.
authors.forename: Masakazu
authors.initials: M
authors.lastname: Tazaki
authors.affiliation: Department of Physiology, Tokyo Dental College, Tokyo 101-0061, Japan. Electronic address: yshibuka@tdc.ac.jp.
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Shibukawa
mesh_terms: D000083:Acetanilides / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002462:Cell Membrane / Q000502:physiology*; D002478:Cells, Cultured; D006224:Cricetinae; D007038:Hypotonic Solutions / Q000494:pharmacology; D040542:Mechanotransduction, Cellular / Q000187:drug effects; D018862:Merkel Cells / Q000166:cytology / Q000378:metabolism*; D009061:Mouth Mucosa / Q000166:cytology; D011687:Purines / Q000494:pharmacology; D013449:Sulfonamides / Q000494:pharmacology; D050052:TRPC Cation Channels / Q000037:antagonists & inhibitors / Q000378:metabolism*; D050916:TRPV Cation Channels / Q000037:antagonists & inhibitors / Q000378:metabolism*
chemical_list: C552888:2-(1,3-dimethyl-2,6-dioxo-1,2,3,6-tetrahydro-7H-purin-7-yl)-N-(4-isopropylphenyl)acetamide; D000083:Acetanilides; D007038:Hypotonic Solutions; D011687:Purines; C544743:RN 1734; D013449:Sulfonamides; D050052:TRPC Cation Channels; D050916:TRPV Cation Channels; D002118:Calcium
keywords: Mechanotransduction; Merkel cell; Sensory transduction; TRP