Permeability of squid axon membrane to various ions.
The permeability of the squid axon membrane was determined by the use of radioisotopes of Na, K, Ca, Cs, and Br. Effluxes of these isotopes were measured mainly by the method of intracellular injection. Measurements of influxes were carried out under continuous intracellular perfusion with an isotonic solution of potassium sulfate. The Na permeability of the resting (excitable) axonal membrane was found to be roughly equal to the K permeability. The permeability to anion was far smaller than that to cations. It is emphasized that the axonal membrane has properties of a cation exchanger. The physicochemical nature of the "two stable states" of the excitable membrane is discussed on the basis of ion exchange isotherms.
D000818:Animals; D001369:Axons; D001966:Bromine; D002127:Calcium Isotopes; D002587:Cesium Isotopes; D049832:Decapodiformes; D007474:Ion Exchange; D007477:Ions; D010539:Permeability; D011188:Potassium; D011194:Potassium Isotopes; D012964:Sodium; D012975:Sodium Isotopes
D002127:Calcium Isotopes; D002587:Cesium Isotopes; D007477:Ions; D011194:Potassium Isotopes; D012975:Sodium Isotopes; D012964:Sodium; D011188:Potassium; D001966:Bromine
AXONS; BROMINE; CALCIUM ISOTOPES; CESIUM ISOTOPES; ION EXCHANGE; PERMEABILITY; POTASSIUM ISOTOPES; SODIUM ISOTOPES