Fig. 3. Electrophysiological features of the neural-induced human mesenchymal stem cells (NI-hMSCs). (A) hMSCs demonstrated neuronal characteristics after neural differentiation under voltage-clamp recording. The holding potential was -80 mV and depolarizing steps were applied from -80 mV to +40 mV in 10 mV increments. Large voltage-dependent sodium currents were activated evidently from a depolarizing step of -30 mV and blocked reversibly by tetrodotoxin (TTX) 100 nM. In addition, the hMSCs grown with basic fibroblast growth factor (bFGF) and forskolin showed sustained outward potassium currents as well. Peak current-voltage relationship was plotted against the voltages and demonstrated the voltage-dependence of potassium currents (IK) and sodium currents (INa) (n=16). (B) Under current clamp condition, the resting membrane potential of NI-hMSCs was recorded more negatively than that of control hMSCs grown without bFGF and forskolin (n=16, ^**P<0.01 compare with primary hMSCs). (C) Expression of molecular markers for ion channel subunits was increased after neural differentiation in hMSCs. The mRNA expression of human large-conductance, voltage- and calcium-dependent K⁺ channel marker, MaxiK; voltage-dependent K⁺ channel marker, Kv1.4, Kv4.2, and Kv4.3; either-à-go-go K⁺ channel marker, Eag1 and Eag2; tetrodotoxin-sensitive Na⁺ channel marker, NE-Na; voltage-dependent L-type Ca2⁺ channel, alpha 1C subunit marker, CACNA1C; and voltage-dependent T-type Ca2⁺ channel, alpha 1G subunit marker, CACNA1G were increased in NI-hMSCs, however, that of TTX-insensitive sodium channel marker, SCN5A were not detected. Reverse transcription-polymerase chain reaction assay was repeated five times independently from different cells. The representative data are shown. (D) The intensity of each gene was normalized to GAPDH and these results were repeated at least three times (^*P<0.05 compared with primary hMSCs).