TEA prevents inactivation while blocking open K+ channels in human T lymphocytes.
The whole-cell recording mode of the patch-clamp technique was used to study the effect of external tetraethylammonium ([TEA+]o) on the inactivating, voltage-dependent K+ channels of human T lymphocytes. TEA+ reduced the peak amplitude and slowed the time course of the K+ current decay during a depolarizing pulse, resulting in a crossover of the current records in the presence and absence of TEA+. In solutions with different [TEA+]o both the peak K+ current amplitude, lKpeak, and the time constant of the decay of the K+ current, tau d, were reduced in a dose-dependent manner, both with apparent binding constants, KD, of 12 mM. The integral of K+ current during a prolonged depolarizing pulse was unaltered in solutions with different [TEA+]o. The concentration dependence of [TEA+]o on lKpeak, tau d, and the unchanged current integral can be explained with a kinetic scheme in which open channels blocked by TEA+ cannot inactivate.
Grissmer
S
S
Department of Physiology and Biophysics, University of California, Irvine 92717.
Cahalan
M
M
D002460:Cell Line; D004594:Electrophysiology / Q000379:methods; D006801:Humans; D007700:Kinetics; D008433:Mathematics; D008564:Membrane Potentials; D008962:Models, Theoretical; D015221:Potassium Channels / Q000187:drug effects / Q000502:physiology*; D013601:T-Lymphocytes / Q000187:drug effects / Q000502:physiology*; D019789:Tetraethylammonium; D013757:Tetraethylammonium Compounds / Q000494:pharmacology*
D015221:Potassium Channels; D013757:Tetraethylammonium Compounds; D019789:Tetraethylammonium