抄録
Mechanism of the pain relief effect of low-power laser (Ga-Al-As diode laser, 16.2mW) irradiation using cultured mouse dorsal root ganglion neurons associated with C-fiber was studied by patch-clamp technique. Bradykinin (BK) and laser stimulations were limited to the process or the cell body (soma) with a separator developed by us. The action potentials of the soma by BK application to the process were reversibly suppressed by the irradiation for 2 min to the process. After the irradiation to the soma was done without BK stimulation, resting potential was depolarized by potential of 2-3 mV, and the frequency of the spike evoked by a depolarization pulse was enhanced, except for the case in which the irradiation was limited to the process. K+ channel openings elicited by BK were reversibly suppressed by the irradiation to the soma. Inward current evoked by a depolarization pulse was not suppressed by the irradiation to the soma. BK-evoked inward currents were suppressed by the irradiation to the process. When BK was applied to the process and the irradiation to the soma was done, the action potentials by BK were not suppressed. The results suggest that the increase in the spike frequency by the irradiation to the soma without BK is ascribed to depolarization due to inhibition of K+ channel openings, and the suppressive effect of laser irradiation on BK-evoked action potential may come from suppression of the system of receptor-G protein in the process. [J Physiol Sci. 2006;56 Suppl:S178]
