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KMID : 0848120020270020069
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International Journal of Oral Biology
2002 Volume.27 No. 2 p.69 ~ p.78
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Electrophysiological Study on Tetrodotoxin-resistant Sodium Current and its Sensitization by Prostaglandin E_2 in Rat Trigeminal Root Ganglion Neurons
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Kim HJ
Kim HC
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Abstract
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Trigeminal root ganglia (TRG) neurons transmit various sensory information such as touch, pressure, pain and temperature from the oral & maxillofacial region to the central nervous system. Ionic channels in neuronal membranes have a fundamental role in the transmission of various sensory impulses. Particularly, sodium channels are important to generation action potentials and classified into TTX-r and TTX-s sodium channels It has been suggested that TTX-r I_Na may participate in the sensitization to noxious stimuli in small capsaicin-sensitive primary afferent to noxious stimuli in small capsaicin-sensitive primary afferent neurons based on its modulation by pain-inducing agents. Therefore this experiment was performed to investigate the ranges of voltage-dependent I_Na in adult rat TRG neurons to a hyperalgesic agent, PGE_2 by using whole-cell patch clamp technique. In conclusion, we identified the voltage-dependent TTX_r and TTX_s sodium channels, and treir activation and inactivation properties are quite different. Although three types of proton-gated I_Na were identified in rat TRG neurons (Pidoplichko, 1992) and TTX_r sodium channels were detected by the in-situ hybridization technique in the same preparation (Akopian et al., 1996), no direct observation of voltage-dependent I_Na has been reported mechanism of a hyperalgesic agent, PGE_2 is due, in part, the increase of TTX_r I_Na and a shift of I-V relationship to a hyperpolarizing direction which means the increased excitability in response to noxious stimuli.
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KEYWORD
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TTX-r I_Na, PGE_2, Trigeminal ganglion neuron
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