title: Two distinct mechanisms are responsible for single K channel block by internal tetraethylammonium ions.
abstract: Tetraethylammonium (TEA) ions blocked the unitary currents through the delayed rectifier potassium channels of Drosophila neurons from the cytoplasmic side of inside-out membrane patches by two distinct mechanisms. First, TEA attenuated the single-channel conductance, probably by producing very rapid block-unblock reactions at the inner mouth of the potassium pore. Second, TEA markedly enhanced the slow inactivation, making the incidence of channel openings highly nonrandom; blank traces with no channel openings during repetitive depolarizations showed a significant tendency to be clustered in the presence of TEA. This second action accounts for almost half of the reduction of average current produced by 10 mM internal TEA.
authors.affiliation: Laboratory of Neurophysiology, Mitsubishi-Kasei Institute of Life Sciences, Tokyo, Japan.
authors.forename: D
authors.initials: D
authors.lastname: Yamamoto
authors.forename: N
authors.initials: N
authors.lastname: Suzuki
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D004330:Drosophila; D007700:Kinetics; D008433:Mathematics; D008564:Membrane Potentials / Q000187:drug effects; D008959:Models, Neurological; D009474:Neurons / Q000502:physiology*; D015221:Potassium Channels / Q000187:drug effects / Q000502:physiology*; D019789:Tetraethylammonium; D013757:Tetraethylammonium Compounds / Q000494:pharmacology*
chemical_list: D015221:Potassium Channels; D013757:Tetraethylammonium Compounds; D019789:Tetraethylammonium