Journal of Neuroscience, Vol 9, 2801-2808, Copyright © 1989 by Society for Neuroscience
Stretch-activated ion channels in growth cones of snail neurons
WJ Sigurdson and CE Morris
Department of Biology, University of Ottawa, Ontario, Canada.
Using single-channel recording, we show that neurons contain ion channels
sensitive to membrane tension. Neurons isolated from the snail, Lymnaea
stagnalis, actively rearborized in culture yielding cell bodies and growth
cones suitable for patch clamping. All neurons contained, in both their
soma and growth cones (at a density of approximately 1-2 micron-2),
stretch-activated channels highly selective for K+. The presence of this
mechanosensitive channel in the motile region of the neuron, a region
characterized by insertion of new membrane--the growth cone--is of
particular interest. Under physiological conditions, the channel was
permeable to K+, but not to Na+ or Cl-. Its conductance to K+ under these
conditions was approximately 44 pS. Channel activation was steeply
dependent on membrane tension, showing thresholds at between -50 to -100 mm
Hg (suction was applied through the recording pipette). Kinetic analysis
indicated that the stretch-dependent increase in the channel's open
probability was related to a long closed state rather than to one of the
open states. Given the importance of Ca2+ in the regulation of growth cone
motility, we speculate that this stretch-activated K+ channel could play a
role in neurite elongation by a tension-dependent modulation of membrane
voltage which in turn would act on voltage-gated Ca2+ channels.
Previous Article | Next Article
