Modulation of Ca V 2.3 Calcium Channel Currents by Eugenol

Eugenol, a natural congener of capsaicin, is a routine analgesic agent in dentistry. We have recently demonstrated the inhibition of Ca V 2.2 calcium channel and sodium channel currents to be molecular mechanisms underlying the analgesic effect of eugenol. We hypothesized that Ca V 2.3 channels are also modulated by eugenol and investigated its mode of action using the whole-cell patch-clamp technique in a heterologous expression system. Eugenol inhibited calcium currents in the E52 cell line, stably expressing the human Ca V 2.3 calcium channels, where TRPV1 is not endogenously expressed. The extent of current inhibition was not significantly different between naïve E52 cells and TRPV1-expressing E52 cells, suggesting no involvement of TRPV1. In contrast, TRPV1 activation is prerequisite for the inhibition of Ca V 2.3 calcium channels by capsaicin. The results indicate that eugenol has mechanisms distinct from those of capsaicin for modulating Ca V 2.3 channels. We suggest that inhibition of Ca V 2.3 channels by eugenol might contribute to its analgesic effect.