A model of the detection of warmth and cold by cutaneous sensors through effects on voltage-gated membrane channels.
Warmth and cold sensations are known to derive from separate warm and cold cutaneous thermoreceptors in the form of differentiated afferent nerves. The firing rate of warm-sensing nerves increases as the temperature increases; the firing rate of cold-sensing nerves increases if the temperature is reduced. I postulate that the primary sensitivity of the warm sensors derives from voltage-gated Ca(2+) membrane channels configured such that an increase in temperature opens channels and increases the ion influx while a reduction in temperature increases the ion influx through voltage-gated Na(+) channels in the cold sensory nerve ends. In either case, the initial cation influx causes a small cellular depolarization that further opens Ca(2+) channels, admitting more cations in a positive feedback process that leads to the depolarization of the membrane, thus initiating an action potential pulse. Monte Carlo calculations based on a well defined model of such processes, which include effects of noise, demonstrate quantitative agreement of the model with an extensive body of data.
Adair
R K
RK
Department of Physics, Yale University, New Haven, CT 06520-8121, USA. adair@hepmail.physics.yale.edu
D002118:Calcium / Q000378:metabolism; D015220:Calcium Channels / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D004594:Electrophysiology; D006801:Humans; D015640:Ion Channel Gating / Q000502:physiology*; D007700:Kinetics; D008954:Models, Biological; D008956:Models, Chemical; D009010:Monte Carlo Method; D015222:Sodium Channels / Q000502:physiology; D013045:Species Specificity; D013696:Temperature; D013997:Time Factors
D015220:Calcium Channels; D015222:Sodium Channels; D002118:Calcium