IK INACTIVATION IN SQUID AXONS IS SHIFTED ALONG THE VOLTAGE AXIS BY CHANGES IN THE INTRACELLULAR PH

The inactivation curve of the delayed rectifier in internally perfused squid giant axons is shifted along the voltage axis by changes in the pH of the internal perfusate. The amplitude of the shift is 9.5 mV per pH unit (6 less than or equal to pHi less than or equal to 10). No saturation of the effect was observed at either end of the pH range. This result suggests that the inactivation gating mechanism has several titratable groups accessible to protons from the intracellular side of the membrane. © 1990, The Biophysical Society. All rights reserved.