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A1356
October 15, 2007
2:00 PM - 4:00 PM
Room Hall D, Area M,
Ca+ Channel Contributes to Capsaicin-Induced Large mEPSCs in Substantia Gelatinosa Neurons of Rat
Chaoran Wu, M.D., Ph.D., Tatsuro Kohno, M.D., Ph.D., Ayako Wakai, M.D., Ph.D., Hiroshi Baba, M.D., Ph.D.
Department of Anesthesiology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
Capsaicin-sensitive neurons in dorsal root ganglia mainly raise C afferent fibers that terminate preferentially on substantia gelatinosa (SG) neurons in the dorsal horn. SG neurons play an important role in the nociceptive transmission from the peripheral to the centre. The action of capsaicin on excitatory transmissions was examined in the SG using the whole-cell patch-clamp technique in the presence of tetrodotoxin (1 μM). Bath-applied capsaicin at a concentration of 2 μM activated many large-amplitude glutamatergic miniature excitatory postsynaptic currents (mEPSCs), which were seldom observed in controls. These large-amplitude mEPSCs were blocked by a voltage-dependent calcium channel blocker, cobalt (4 mM). However, increases in mEPSCs frequency induced by capsaicin were little changed by cobalt. Our results indicate that the voltage-dependent calcium channel may contribute to the generation of capsaicin-induced large-amplitude mEPSCs.

Anesthesiology 2007; 107: A1356