MECHANOSENSITIVE PROPERTIES OF BK CHANNELS FROM EMBRYONIC RAT NEUROEPITHELIUM

The mechanosensitive properties of large-conductance Ca2+-activated K (BK) channels from embryonic rat neuroepithelium were investigated wi th the cell-attached and inside-out configurations of the patch-clamp technique, The channels were activated in both recording configuration s by negative pressures applied to the patch electrode, but reversal o f the effect was total and immediate in inside-out patches whereas it was incomplete and delayed in on-cell patches, This mechanosensitivity was not mediated by Ca2+ ions or fatty acids, suggesting that it is a n intrinsic property of these channels, Cytochalasin B did not affect mechanosensitivity in on-cell patches but increased it in inside-out p atches, Kinetic studies showed that stretch increased the mean open ti me of the channels and decreased the slowest time constant of their cl osed-time distributions, The present as well as previous results sugge st complex interactions between embryonic BK channels and their membra nous and submembranous environment.