Stretch-activated cation channels in human fibroblasts.
Nonconfluent fibroblasts are relatively depolarized when compared with confluent fibroblasts, and transient hyperpolarizations result from a range of external stimuli as well as internal cellular activities. This electrical activity ceases, along with growth and mitogenic activity, when the cells become confluent. A calcium-activated potassium conductance is thought to be responsible for these hyperpolarizations, but in human fibroblasts the large calcium-activated potassium channel is not stretch-activated. We report here the identification of single stretch-activated cation channels in human fibroblasts, using the cell-attached and inside-out patch clamp techniques. The most prominent channel had a conductance of approximately 60 pS (picoSeimens) in 140 mM potassium and was permeable to potassium and sodium. The channel showed significant adaptation of activity when stretch was maintained over a period of several seconds, but a static component persisted for much longer periods. Higher conductance channels were also observed in a few excised patches.
Stockbridge
L L
LL
Department of Physiology, University of Alberta, Edmonton, Canada.
French
A S
AS
D002412:Cations; D002460:Cell Line; D002478:Cells, Cultured; D004553:Electric Conductivity; D005347:Fibroblasts / Q000502:physiology*; D006801:Humans; D007473:Ion Channels / Q000502:physiology*; D008564:Membrane Potentials; D012879:Skin Physiological Phenomena
D002412:Cations; D007473:Ion Channels