The Effect of High Extracellular Potassium on the Kinetics of Potassium Conductance of the Squid Axon Membrane

K currents were studied under voltage clamp in intact axons or in axons perfused intracellularly with solutions containing 300 meq-K+, sucrose and phosphate ions at pH 7.3. The axons were superfused with extracellular solutions containing: (460 − x) mM-NaCl (or TMACl); x mM-KCl; 50 mM-CaC12; .5 μM-TTX; 5 mM-TrisCl buffer; pH 7.8; 0≦x≦460.