Modulation of voltage-activated calcium currents by mechanical stimulation in rat sensory neurons.
We examined the effects of mechanical stress, induced by a stream of bath solution, on evoked action potentials, electrical excitability, and Ca2+ currents in rat dorsal root ganglion neurons in culture with the use of the whole cell patch-clamp technique. Action-potential duration was altered reversibly by flow in 39% of the 51 neurons tested, but membrane potential and excitability were unaffected. The flow-induced increases and decreases in action-potential duration were consistent with the different effects of flow on two types of Ca2+ channel, determined by voltage-clamp recordings of Ba2+ currents. Current through omega-conotoxin-sensitive (N-type) Ca2+ channels increased by an estimated 74% with flow, corresponding to 23% increase in the total high voltage-activated current, whereas current through low-threshold voltage-activated (T-type) channels decreased by 14%. We conclude that modulation of voltage-activated Ca2+ currents constitutes a route by which mechanical events can regulate Ca2+ influx in sensory neurons.
Sobell Department of Neurophysiology, Institute of Neurology, London WC2N 3BG, United Kingdom.
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Bouskila
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Bostock
D000200:Action Potentials / Q000502:physiology; D000818:Animals; D001464:Barium / Q000502:physiology; D002118:Calcium / Q000502:physiology*; D002478:Cells, Cultured; D004553:Electric Conductivity; D004594:Electrophysiology; D005727:Ganglia, Spinal / Q000166:cytology; D007700:Kinetics; D008297:Male; D009475:Neurons, Afferent / Q000502:physiology*; D018408:Patch-Clamp Techniques; D051381:Rats; D017208:Rats, Wistar; D013314:Stress, Mechanical
D001464:Barium; D002118:Calcium