Abstract: Objective · To provide electrophysiological evidence for RIN-14B cells as an useful model of enterochromaffin cells (EC) and to study the role of Nav1.3 channel in the control of its excitability. Methods · Resting membrane potential was recorded and the effects of TTX and ICA-121431 were examinedcurrent-clamp in cultured RIN-14B cells. The effects of TTX and ICA-121431 on Na+ current of RIN-14B cells were examinedvoltage-clamp. Results · RIN-14B cells had a resting potential around -60 mV and fired action potentials when stimulated with depolarizing current pulses. The action potential was completely blockedTTX and inhibitedICA-121431 in a dose-dependent manner. TTX blocked activation and inactivation of sodium current. In addition ICA-121431 dose-dependently inhibited activation of Na+ current. Conclusion · The action potential of RIN-14B cells is inducedTTX-sensitive sodium channel and the excitability is controlledNav1.3. These results suggest RIN-14B cells are similar to EC and it may be a good model of EC.

Key words: RIN-14B cell, Nav1.3, enterochromaffin cell, tetrodotoxin, ICA-121431