External and internal effects of tetraethylammonium on voltage-dependent and Ca-dependent K+ currents components in molluscan pacemaker neurons.
Ca-dependent and voltage-dependent K+ currents in Aplysia pacemaker neurons were studied separately by electrophoretic injections of Ca2+ ions into the cells to induce the Ca-dependent component and by step depolarizations in the absence of external Ca2+ ions to induce the voltage-dependent component. Intracellular tetraethylammonium (TEA) blocks the voltage-dependent but not the Ca-dependent K+ current. Extracellular TEA blocks both components reversibly but is more effective in inhibiting the Ca-dependent K+ currents. Our results suggest that there are TEA receptor sites for the voltage-dependent K+ current on each side of the membrane, but only an external receptor site for the Ca-dependent K+ current.
D000818:Animals; D001048:Aplysia; D002118:Calcium / Q000494:pharmacology; D002463:Cell Membrane Permeability / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D008564:Membrane Potentials; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism; D011188:Potassium / Q000378:metabolism*; D011955:Receptors, Drug / Q000378:metabolism; D013757:Tetraethylammonium Compounds / Q000494:pharmacology*
D011955:Receptors, Drug; D013757:Tetraethylammonium Compounds; D011188:Potassium; D002118:Calcium