title: Activation of a cation conductance by acetic acid in taste cells isolated from the bullfrog.
abstract: The ionic mechanism of the conductance activated by acetic acid was analyzed in isolated bullfrog taste cells under whole-cell voltage-clamp. Bath-application of acetic acid (pH 3.9-4.7) induced an inward current in about 80% of the taste cells. The current occurred in external 80 mmol l-1 Ba2+ and internal 100 mmol l-1 Cs+, which completely blocked the delayed outward K+ current. The concentration-response relationship for the acid-activated current was consistent with that of the gustatory neural response. Prolonged adaptation of the surface of the tongue to HCl prior to taste cell isolation decreased the acid-induced current to about 20% of the control value without decreasing NaCl-induced neural responses and voltage-activated Na+ currents. The results suggest that the transduction mechanism of the acid response might be different from that of the response to salt. The I-V relationship of the acid-induced response was nearly linear at membrane potentials between -80 and 80 mV. The acid-induced conductance was permeable to alkali metal and alkali earth metal ions. The permeability ratios were PCa:PBa:PSr:PNa:PCs = 1.87:1.17:0.73:0.99:1.00. The present study suggests that the acid-induced receptor current in bullfrog taste cells is generated by an increase in a cation conductance in the apical taste membrane.
authors.affiliation: Department of Physiology, Nagasaki University School of Dentistry, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Okada
authors.forename: T
authors.initials: T
authors.lastname: Miyamoto
authors.forename: T
authors.initials: T
authors.lastname: Sato
mesh_terms: D000085:Acetates / Q000494:pharmacology*; D019342:Acetic Acid; D000818:Animals; D001464:Barium / Q000502:physiology; D002586:Cesium / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D008564:Membrane Potentials / Q000187:drug effects; D011188:Potassium / Q000502:physiology; D011892:Rana catesbeiana / Q000502:physiology*; D012964:Sodium / Q000502:physiology; D009435:Synaptic Transmission / Q000187:drug effects*; D013650:Taste Buds / Q000166:cytology* / Q000187:drug effects / Q000502:physiology
chemical_list: D000085:Acetates; D002586:Cesium; D001464:Barium; D012964:Sodium; D019342:Acetic Acid; D011188:Potassium