Involvement of actin cytoskeleton in modulation of Ca2+-activated K+ channels from rat hippocampal CA1 pyramidal neurons

Using inside-out configuration of patch clamp techniques, actin cytoskeleton modulation of large conductance calcium-activated potassium (BKca) channels was studied in hippocampal CA1 pyramidal neurons from adult rat. Disruption of actin filament after brief treatment with cytochalasin D (CD) markedly decreased activity of BKca channels and this inhibitory action persisted even after CD washout. This CD-produced decrease in BKCa channel activity was characterized by a shortened open lifetime and reduced opening frequency. Disruption of actin filament with another toxin cytochalasin B also exerted similar effects as CD. Phalloidin, the actin filament stabilizer, had no significant effect on BKCa channel activity, while pre-treatment with phalloidin could prevent the CD-induced inhibitory effect on channel activity. The present study demonstrates that disruption of actin cytoskeleton can inhibit BKCa channel activity, suggesting that BKca channels in rat hippocampal CA1 pyramidal neurons may be directly modulated by dynamic assembly and disassembly of submembranous actin cytoskeleton. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved.