Ion channels activated by cold and menthol in cultured rat dorsal root ganglion neurones.
A cold- and menthol-activated ionic current has been described in sensory neurones, which probably has a role in temperature sensing. Here we describe the ion channels underlying this current. Cooling activated non-selective cation channels (conductance, about 22 pS; reversal potential, -4.2 mV) in outside-out patches from cold-sensitive rat dorsal root ganglion neurones, and their activity was strongly increased by menthol. The activation threshold was 17.9 degrees C, shifting to 24.3 degrees C in 100 microM (-)-menthol, about 10 degrees C colder than observed in intact neurones. Channels in excised patches did not adapt to sustained cooling, unlike the current in intact neurones. We conclude that the ion channels underlying the cold- and menthol-induced current are directly activated by these stimuli, although other modulatory factors appear to be important in determining threshold and adaptation.
Reid
Gordon
G
Department of Animal Physiology and Biophysics, Faculty of Biology, University of Bucharest, Splaiul Independenţei 91-95, 76201 Bucharest, Romania. gordon@biologie.kappa.ro
Flonta
Maria-Luiza
ML
D000222:Adaptation, Physiological / Q000187:drug effects / Q000502:physiology; D000818:Animals; D002478:Cells, Cultured; D003080:Cold Temperature; D005727:Ganglia, Spinal / Q000166:cytology / Q000502:physiology*; D007036:Hypothermia, Induced; D007473:Ion Channels / Q000187:drug effects / Q000502:physiology*; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D008610:Menthol / Q000494:pharmacology*; D009431:Neural Conduction / Q000187:drug effects / Q000502:physiology; D009475:Neurons, Afferent / Q000166:cytology / Q000502:physiology*; D017729:Presynaptic Terminals / Q000187:drug effects / Q000502:physiology; D051381:Rats; D012684:Sensory Thresholds / Q000187:drug effects / Q000502:physiology; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D012867:Skin / Q000294:innervation*; D013697:Thermosensing / Q000187:drug effects / Q000502:physiology*
D007473:Ion Channels; D008610:Menthol