The Journal of Neuroscience, February 15, 2002, 22(4):1238-1247
Mechanosensitive Ion Channels in Cultured Sensory Neurons of
Neonatal Rats
Hawon
Cho,
Jieun
Shin,
Chan Young
Shin,
Soon-Youl
Lee, and
Uhtaek
Oh
The Sensory Research Center, Creative Research Initiatives, College
of Pharmacy, Seoul National University, Seoul 151-742, Korea
Mechanosensitive (MS) ion channels are present in a variety of
cells. However, very little is known about the ion channels that
account for mechanical sensitivity in sensory neurons. We identified
the two most frequently encountered but distinct types of MS channels
in 1390 of 2962 membrane patches tested in cultured dorsal root
ganglion neurons. The two MS channels exhibited different thresholds,
thus named as low-threshold (LT) and high-threshold (HT) MS channels,
and sensitivity to pressure. The two channels retained different
single-channel conductances and current-voltage relationships: LT and
HT channels elicited large- and small-channel conductance with
outwardly rectifying and linear I-V relationships, respectively. Both LT and HT MS channels were permeable to monovalent cations and Ca2+ and were blocked by gadolinium, a
blocker of MS channels. Colchicine and cytochalasin D markedly reduced
the activities of the two MS channels, indicating that cytoskeletal
elements support the mechanosensitivity. Both types of MS channels were
found primarily in small sensory neurons with diameters of <30 µm.
Furthermore, HT MS channels were sensitized by a well known inducer of
mechanical hyperalgesia, prostaglandin E2, via the
protein kinase A pathway. We identified two distinct types of MS
channels in sensory neurons that probably give rise to the observed MS
whole-cell currents and transduce mechanical stimuli to neural signals
involved in somatosensation, including pain.
Key words:
mechanosensitive channels; cationic; sensory neurons; somatosensation; pain; sensitization
Copyright © 2002 Society for Neuroscience 0270-6474/02/2241238-10$05.00/0
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