Ionic conductance changes in voltage clamped crayfish axons at low pH.

摘要: Giant axons from the crayfish have been voltage clamped with an axial wire system. General characterististics of observed ionic currents under normal conditions are similar to those measured in other giant and nodes Ranvier. As pH external bath is lowered below 7, a marked, reversible slowing potassium seen little effect on sodium currents. The steady-state conductance-voltage curve shifted along axis manner consistent development hyperpolarizing surface charge. Results suggest that this potential shift accounts for part, though not all, increase τn. From behavior kinetics delayed current these alterations conductance attributed titration histidine imidazole residue membrane protein. Chemical modification by carbethoxylation at 6 slows strongly depresses results addition introduction electrostatic forces, possibly resulting charge, protonation group low also alters nonelectrostatic chemical interactions determining ease which gates open close. evidence indicates modified closely associated components involved control conductance.