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Figure 1. Single-channel currents and current-voltage (I-V) relationships of TREK-1 K⁺ channels obtained from human PDL fibroblasts. (A) Current traces from an inside-out patch. Voltages on the left are negative pipette potentials, i.e., in inside-out mode, the voltage values show absolute potentials of the patch membrane (V_m). Horizontal lines to the right of each trace indicate the closed state. Inward currents are downward. Both pipette solution and bath solutions were the high-K⁺ solution. The bath solution contained 3 µM arachidonic acid. (B) I-V relationships obtained from inside-out patches. Currents were recorded from patches given a serial voltage pulse every 20 mV between -100 mV and 100 mV. Negative current is inward. Datapoints show means ± SD. The solid line indicates the I-V relationship obtained from inside-out patches in symmetrical high-K⁺ solutions (n = 11). The I-V relationship can be fitted to a regression line, current = 0.104 V_m + 0.022 (R² = 0.999), showing that the single-channel slope conductance of the TREK-1 K⁺ channel is 104 pS. The dotted line indicates the I-V relationship obtained from several patches from among the same patches, the bath solution of which was exchanged to the high-Na⁺ solution by perfusion, and currents were recorded again for the serial voltage pulses (n = 8). The I-V relationship showed a slight inward rectification (that is, the I-V relationship is not linear and binding). As the voltage rose, the currents became too small to be detected, but the currents recorded at voltages lower than the reversal potential of the potassium ion (about 83 mV) flowed inwardly. The dashed line indicates the I-V relationship obtained from patches with high-Na⁺ pipette solution and high-K⁺ bath solution (n = 9). The I-V relationship showed a slight outward rectification, and distinct inward currents could not be detected, but the currents flowed outwardly at voltages higher than the reversal potential of the potassium ion (about -83 mV). These results show that the channel is a K⁺-selective channel.

J DENT RES, Vol. 85, No. 7, 664-669 (2006)
DOI: 10.1177/154405910608500716

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