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Eugenol Inhibits K+ Currents in Trigeminal Ganglion Neurons
1 Department of Physiology and Program in Molecular and Cellular Neuroscience, School of Dentistry and Dental Research Institute, Seoul National University, 28-2 Yeongeon-Dong Chongno-Ku, Seoul 110-749, Korea; and Correspondence: * corresponding author, odolbae{at}snu.ac.kr Eugenol, a natural capsaicin congener, is widely used in dentistry. Eugenol inhibits voltage-activated Na+ and Ca2+ channels in a transient receptor potential vanilloid 1 (TRPV1)-independent manner. We hypothesized that eugenol also inhibits voltage-gated K+ currents, and investigated this in rat trigeminal ganglion neurons and in a heterologous system using whole-cell patch clamping. Eugenol inhibited voltage-gated K+ currents, and the inhibitory effects of eugenol were observed in both capsaicin-sensitive and capsaicin-insensitive neurons. Pre-treatment with capsazepine, a well-known antagonist of TRPV1, failed to block the inhibitory effects of eugenol on K+ currents, suggesting no involvement of TRPV1. Eugenol inhibited human Kv1.5 currents stably expressed in Ltk– cells, where TRPV1 is not endogenously expressed. We conclude that eugenol inhibits voltage-gated K+ currents in a TRPV1-independent manner. The inhibition of voltage-gated K+ currents is likely to contribute to the irritable action of eugenol. Abbreviations: human Kv1.5 channel, hKv1.5; transient receptor potential vanilloid 1, TRPV1.
Key Words: eugenol trigeminal ganglion neurons voltage-gated K+ currents Kv1.5
Journal of Dental Research, Vol. 86, No. 9,
898-902 (2007) |
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