title: The action of external tetraethylammonium ions on unitary delayed rectifier potassium channels of frog skeletal muscle.
abstract: 1. We have used single-channel recording to investigate the block by extracellular tetraethylammonium ions (TEA+) of delayed rectifier potassium channels of frog skeletal sarcolemma. 2. TEA+ blocks by reducing the apparent amplitude of unitary currents, without detectable increase in open-level current variance. 3. The block by TEA+ appeared to be 1:1, the fractional current being halved at 5.8 mM and -3 mV. The dissociation constant for the block was voltage dependent, increasing e-fold for a 138 mV depolarization. 4. Activation of delayed rectifier potassium currents is not altered by TEA+. 5. Open times, which in the presence of TEA+ represents bursts of open and blocked events, are not increased by TEA+, indicating that blocked channels are able to close normally.
mesh_terms: D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D066298:In Vitro Techniques; D007473:Ion Channels / Q000187:drug effects*; D009132:Muscles / Q000502:physiology*; D011188:Potassium / Q000502:physiology*; D011896:Rana temporaria; D019789:Tetraethylammonium; D013757:Tetraethylammonium Compounds / Q000494:pharmacology*; D013997:Time Factors
chemical_list: D007473:Ion Channels; D013757:Tetraethylammonium Compounds; D019789:Tetraethylammonium; D011188:Potassium