title: 4-Aminopyridine reduces chorda tympani nerve taste responses to potassium and alkali salts in rat.
abstract: To study the potential role of potassium channels in the taste response to potassium salts, we applied 4-aminopyridine (4-AP) to the anterior rat tongue and recorded chorda tympani nerve taste responses to chemical stimuli. 4-aminopyridine is a pharmacological blocker that reduces potassium conductance through potassium channels in nerve and muscle. Summated neural responses to stimuli dissolved in water and in 4-AP were compared. Chemical stimuli included concentration ranges of KCl, KBr, KH2PO4, CsCl, RbCl, NH4Cl, NaCl and sucrose. The blocker reduced chorda tympani responses to KCl and other potassium salts, from 0.025 to 0.25 M. Responses to ammonium, rubidium and cesium salts also were reduced, in order of effectiveness that would be predicted from known ion selectivity properties of potassium channels. Responses to NaCl and sucrose were not reduced. Other channel blockers, including tetraethylammonium chloride (TEA), BaCl2 and quinidine, did not reduce the response to KCl. These are the first detailed reports of effects of potassium channel blockers on the peripheral, neural taste response. The results are consistent with a role for potassium channels in apical taste bud cell membranes in transduction for potassium salts.
authors.affiliation: Department of Biologic and Materials Sciences, School of Dentistry, University of Michigan, Ann Arbor 48109.
authors.forename: M
authors.initials: M
authors.lastname: Kim
authors.forename: C M
authors.initials: CM
authors.lastname: Mistretta
mesh_terms: D015761:4-Aminopyridine / Q000494:pharmacology*; D000468:Alkalies / Q000494:pharmacology*; D000818:Animals; D001464:Barium / Q000494:pharmacology; D017609:Barium Compounds; D002586:Cesium / Q000494:pharmacology; D002712:Chlorides / Q000494:pharmacology; D002814:Chorda Tympani Nerve / Q000187:drug effects*; D005260:Female; D008012:Lidocaine / Q000494:pharmacology; D008297:Male; D011188:Potassium / Q000494:pharmacology*; D015221:Potassium Channels / Q000187:drug effects; D011189:Potassium Chloride / Q000494:pharmacology; D011802:Quinidine / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012413:Rubidium / Q000494:pharmacology; D012965:Sodium Chloride / Q000494:pharmacology; D013395:Sucrose / Q000494:pharmacology; D013649:Taste / Q000187:drug effects*; D013757:Tetraethylammonium Compounds / Q000494:pharmacology; D014059:Tongue / Q000187:drug effects
chemical_list: D000468:Alkalies; D017609:Barium Compounds; D002712:Chlorides; D015221:Potassium Channels; D013757:Tetraethylammonium Compounds; C024986:barium chloride; D002586:Cesium; D001464:Barium; D012965:Sodium Chloride; D013395:Sucrose; D011189:Potassium Chloride; D008012:Lidocaine; D015761:4-Aminopyridine; C028019:cesium chloride; D011802:Quinidine; D012413:Rubidium; C032710:rubidium chloride; D011188:Potassium