Molecular Nociception Group, Wolfson Institute for Biomedical Research, University College London, London, UK.
J Physiol. 2010 Jan 15;588(Pt 2):301-14. doi: 10.1113/jphysiol.2009.182360. Epub 2009 Nov 30.
Dorsal root ganglion neurons in vitro express a number of types of mechanically activated currents that are thought to underlie somatic mechanosensory transduction in vivo. We have studied the inactivation properties of these currents to assess how they might influence the electrophysiological responses of dorsal root ganglion (DRG) neurons to mechanical stimulation. We show that the speed of ramp-like mechanical stimulation determines the dynamics of mechanically activated current responses and hence the type of DRG neuron most likely to be activated. We also show that both rapidly and slowly adapting currents inactivate as a function of membrane stretch. However, the rapidly adapting current inactivation time course is mainly dependent on channel opening whilst slowly adapting current kinetics are dependent on membrane stretch. In response to repeated stimulation, slowly adapting currents inactivate less and recover more quickly than rapidly adapting currents. Therefore, vibratory stimuli tend to inactivate rapidly adapting currents whilst static stimuli tend to inactivate slowly adapting currents. Current clamp experiments show that, physiologically, the response of different types of sensory neurons is dictated primarily by the static or dynamic nature of the mechanical stimulus and the interplay between voltage-gated and mechanically gated ion channels expressed in these neurons.
背根神经节神经元在体外表达多种类型的机械激活电流，这些电流被认为是体内躯体机械感觉转导的基础。我们研究了这些电流的失活特性，以评估它们如何影响背根神经节 (DRG) 神经元对机械刺激的电生理反应。我们表明，类似斜坡的机械刺激的速度决定了机械激活电流反应的动力学，因此最有可能激活的 DRG 神经元类型。我们还表明，快速和缓慢适应电流都会随着膜拉伸而失活。然而，快速适应电流的失活时程主要取决于通道的开启，而缓慢适应电流动力学取决于膜拉伸。在重复刺激下，缓慢适应电流失活较少，恢复较快。因此，振动刺激往往会使快速适应电流失活，而静态刺激则往往会使缓慢适应电流失活。电流钳实验表明，在生理上，不同类型的感觉神经元的反应主要由机械刺激的静态或动态特性以及这些神经元中表达的电压门控和机械门控离子通道之间的相互作用决定。
