Stretch-stimulated activity of large conductance calcium-activated potassium channels in human retinal pigment epithelial cells.
OBJECTIVE
The aim of this study was to investigate the effect of membrane stretch on the activity of BK(Ca) channels and determine whether change in BK(Ca)-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 Ca(2+)-activated K(+) (BK(Ca)) channels in human retinal pigment epithelial (RPE) cells were investigated using the patch-clamp technique.


RESULTS
In cell-attached patches, an increase in BK(Ca)-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 BK(Ca) channels; however, it did enhance the channel activity. Membrane stretch-induced channel activity was found to be independent of the level of intracellular Ca(2+). Membrane stretch also potentiated riluzole-stimulated BK(Ca)-channel activity.


CONCLUSIONS
BK(Ca) channel can be stimulated by membrane stretch in human RPE cells. During an increase in tensile strength of RPE, the BK(Ca) channel might exert a protective action against deleterious tension by promoting a hyperpolarizing outflow that forces the cell to rest.
Sheu
Shwu-Jiuan
SJ
Department of Ophthalmology, Kaohsiung Veterans General Hospital, Kaohsiung City, Taiwan, Republic of China. sjsheu@vghks.gov.tw
Wu
Sheng-Nan
SN
Hu
Dan-Ning
DN
D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism* / Q000502:physiology; D004847:Epithelial Cells / Q000378:metabolism* / Q000502:physiology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D006801:Humans; D051036:Large-Conductance Calcium-Activated Potassium Channels / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D010857:Pigment Epithelium of Eye / Q000166:cytology / Q000378:metabolism* / Q000502:physiology; D019782:Riluzole / Q000494:pharmacology; D013718:Tensile Strength / Q000502:physiology
D018691:Excitatory Amino Acid Antagonists; D051036:Large-Conductance Calcium-Activated Potassium Channels; D019782:Riluzole