title: Survival of K+ permeability and gating currents in squid axons perfused with K+-free media.
abstract: K+ currents were recorded in squid axons internally perfused with impermeant electrolyte. Total absence of permeant ions inside and out leads to an irreversible loss of potassium conductance with a time constant of approximately 11 min at 8 degrees C. Potassium channels can be protected against this effect by external K+, Cs+, NH4+, and Rb+ at concentrations of 100-440 mM. These experiments suggest that a K+ channel is normally occupied by one or more small cations, and becomes nonfunctional when these cations are removed. A large charge movement said to be related to K+ channel gating in frog skeletal muscle is absent in squid giant axons. However, deliberate destruction of K+ conductance by removal of permeant cations is accompanied by measurable loss in asymmetric charge movement. This missing charge component is large enough to contain a contribution from K+ gating charge movements of more than five elementary charges per channel.
mesh_terms: D000818:Animals; D001369:Axons / Q000502:physiology*; D002586:Cesium / Q000494:pharmacology; D049832:Decapodiformes; D004594:Electrophysiology; D066298:In Vitro Techniques; D007473:Ion Channels / Q000187:drug effects / Q000502:physiology*; D011188:Potassium / Q000494:pharmacology; D000644:Quaternary Ammonium Compounds / Q000494:pharmacology; D012413:Rubidium / Q000494:pharmacology
chemical_list: D007473:Ion Channels; D000644:Quaternary Ammonium Compounds; D002586:Cesium; D012413:Rubidium; D011188:Potassium