Aim: The aim of this study was to investigate the effect of membrane stretch on the activity
of BKCa channels and determine whether change in BKCa-channel activity induced by
membrane stretch can be altered in the presence of riluzole.
Methods: The effect and mechanisms of membrane stretch on the activity of large-conductance
Ca2+-activated K+ (BKCa) channels in human retinal pigment epithelial (RPE) cells were
investigated using the patch-clamp technique.
Results: In cell-attached patches, an increase in BKCa-channel activity was induced by membrane
stretch, which is mainly mediated by the increase in the number of long-lived openings.
With inside-out patches, application of pipette suction did not modify single-channel
conductance of BKCa channels; however, it did enhance the channel activity. Membrane
stretch-induced channel activity was found to be independent of the level of intracellular
Ca2+. Membrane stretch also potentiated riluzole-stimulated BKCa-channel activity.
Conclusions: BKCa channel can be stimulated by membrane stretch in human RPE cells. During
an increase in tensile strength of RPE, the BKCa channel might exert a protective action against
deleterious tension by promoting a hyperpolarizing outflow that forces the cell to rest.
