Fig. 4. RT-PCR analysis and electrophysiological property of K2P channels in the SG region.

(A) The mRNA expression of two pore domain K channels (TREK1, TREK2, TRAAK, and TASK3) was observed in SG. Of TASK family, mRNA expression of TASK1 and 3 was only detected in SG, while TASK2 and 5 were not found. Arrow heads indicate 200 and 300 bp, and each size of RT-PCR products is as follows; β-actin 252 bp, TRAAK 198 bp, TREK1 194 bp, TREK2 201 bp, TASK1 244 bp, TASK2 157 bp, TASK3 194 bp, and TASK5 176 bp. (B) The effect of acidic pH on DAMGO-induced current. Low pH (pH 6.4) blocked DAMGO-induced current and increment of slope conductance by DAMGO was reduced in pH 6.4 condition. (C) The effect of Zn²⁺ on DAMGO-induced current. In some SG neurons (n=4/7), application of ZnCl₂ (100 µM) blocked DAMGO-induced current, while others were not altered by ZnCl₂ (n=3/7).