title: Apical localization of K+ channels in taste cells provides the basis for sour taste transduction.
abstract: Previous studies have shown that mudpuppy taste receptor cells respond to sour taste stimuli (weak acids) with depolarizing receptor potentials or action potentials that are blocked by the K+ channel blocker tetraethylammonium. Voltage-clamp recordings from isolated taste cells indicated that taste receptor cells exhibit a variety of voltage-dependent conductances and that acids reduce a voltage-dependent K+ current. Since taste stimuli are restricted to the apical surface of the intact tongue, only 1-2% of the taste receptor cell surface is exposed to chemical stimuli. Thus, modification of a K+ conductance would be an effective transduction mechanism in receptor cells only if the majority of K+ channels were located on the apical membrane. We have used a combination of "loose-patch" and whole-cell recording methods to map the distribution of voltage-sensitive K+ and Na+ channels on dissociated Necturus maculosus taste cells. We report here that the K+ conductance is approximately equal to 50-fold greater on apical membrane than on basolateral membrane, whereas the Na+ conductance is distributed evenly. The marked nonuniformity of the voltage-sensitive K+ conductance, together with the block of this conductance by sour stimuli, indicates that K+ current modulation is the mechanism of sour taste transduction.
authors: Department of Anatomy and Neurobiology, Colorado State University, Fort Collins 80523.
authors: S C
authors: SC
authors: Kinnamon
authors: V E
authors: VE
authors: Dionne
authors: K G
authors: KG
authors: Beam
mesh_terms: D000818:Animals; D007473:Ion Channels / Q000032:analysis*; D009337:Necturus; D011188:Potassium / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism; D013649:Taste / Q000502:physiology*; D013757:Tetraethylammonium Compounds / Q000494:pharmacology
chemical_list: D007473:Ion Channels; D013757:Tetraethylammonium Compounds; D012964:Sodium; D011188:Potassium