THE GATING OF HUMAN RED-CELL CA-2+-ACTIVATED K+-CHANNELS IS STRONGLY AFFECTED BY THE PERMEANT CATION SPECIES

Using inside-out patches, the effect of various permeant cations on the gating behavior of the human red cell Ca2+-activated K+-channel was examined. For symmetric solutions the dwell time histograms indicated two shut and two open states. Mean open times as well as the open-state probability were affected by the permeant cation species: Rb+ stabilised the channel in the open configuration, whereas NH4+ had a destabilising effect. Intermediate stability was obtained in K+ solutions. Bi-ionic experiments indicated that the gating was influenced by the ion species occupying the channel, rather than by ions bound to external modifier sites. © 1990.