title: Dye-permeable, voltage-gated channel on mouse fungiform taste bud cells.
abstract: We show here the expression, permeability and pharmacology of a voltage-gated channel in certain taste bud cells (TBCs) which is known to be permeable to Lucifer Yellow CH (LY) and known to release ATP as a neurotransmitter in response to taste substances. LY dissolved in a 200 mM K(+)-containing solution label TBCs immunoreactive to PLCβ2, a phospholipase subtype, but not the TBC subtype immunoreactive to SNAP-25, a SNARE protein. In addition to these subtypes, LY also labelled a few of the non-immunoreactive TBCs. Monovalent and divalent anion probes with molar mass less than 1200 also label PLCβ2-immunoreactive TBCs and a few non-immunoreactive TBCs, whereas a cation probe, rhodamine B, labels the cell membrane of TBCs nonselectively and K(+) independently. The number of LY-labelled TBCs is decreased by 5 μM DIDS (4,4'-diisothiocyanostilbene-2-2'disulfonate), 1mM octanol and 10(-5)M H(+), but not by 10 μM carbenoxolone, 2mM probenecid, 10mM TEA, or 30 μM flufenamic acid. PLCβ2-immunoreactive TBCs and a few non-immunoreactive TBCs generate a TEA-insensitive outwardly rectifying current. DIDS decreases this current in magnitude with IC(50) of ~0.4 μM in a voltage-independent manner. Also 10(-5)M H(+) and 1mM octanol decreases the current magnitude, but 10 μM carbenoxolone and 2mM probenecid do not. These results show that the LY-permeable channel preferably permeates anions and occurs not only on PLCβ2-immunoreactive TBCs but also on certain non-immunoreactive TBCs. Also the results show that the pharmacology of the LY-permeable channel is different from hemichannels reported. The discussion focuses on the pharmacology and the role of the LY-permeable channel.
authors.affiliation: Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, Hibikino 2-4, Kitakyushu 808-0196, Japan.
authors.forename: Keita
authors.initials: K
authors.lastname: Takeuchi
authors.forename: Yasuhisa
authors.initials: Y
authors.lastname: Seto
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Ohtubo
authors.forename: Kiyonori
authors.initials: K
authors.lastname: Yoshii
mesh_terms: D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000494:pharmacology; D000818:Animals; D001703:Biophysics / Q000379:methods; D002229:Carbenoxolone / Q000494:pharmacology; D004558:Electric Stimulation / Q000379:methods; D005439:Flufenamic Acid / Q000494:pharmacology; D005456:Fluorescent Dyes / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000187:drug effects; D015640:Ion Channel Gating / Q000187:drug effects / Q000502:physiology*; D007546:Isoquinolines / Q000378:metabolism; D008239:Lysine / Q000031:analogs & derivatives / Q000378:metabolism; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology*; D051379:Mice; D009433:Neural Inhibition / Q000187:drug effects / Q000502:physiology; D054799:Phospholipase C beta / Q000378:metabolism; D026902:Potassium Channel Blockers / Q000494:pharmacology; D011984:Sensory Receptor Cells / Q000187:drug effects / Q000378:metabolism*; D050825:Synaptosomal-Associated Protein 25 / Q000378:metabolism; D013650:Taste Buds / Q000166:cytology*; D019789:Tetraethylammonium / Q000494:pharmacology; D013997:Time Factors
chemical_list: D005456:Fluorescent Dyes; D007546:Isoquinolines; D026902:Potassium Channel Blockers; C494209:Snap25 protein, mouse; D050825:Synaptosomal-Associated Protein 25; D005439:Flufenamic Acid; D019789:Tetraethylammonium; C017475:lucifer yellow; D054799:Phospholipase C beta; C013411:biocytin; D008239:Lysine; D002229:Carbenoxolone; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid