Figure 5
From: Expression of truncated Kir6.2 promotes insertion of functionally inverted ATP-sensitive K+ channels
Whole-cell currents recorded from HEK293-cells expressing of different Kir6.2 variants. (A) Current–voltage (I–V) relationships of whole-cell currents in the presence of extracellular solution (denoted control), and 1 mM ATP or 10 µM thimerosal, as indicated. The cells were voltage-clamped at 0 mV (holding potential Vh) for 25 ms prior to and following each pulse, and subsequently pulsed in steps of +10 mV for 150 ms, starting from −100 mV to +150 mV. (B), summary of normalized whole-cell currents of 6xHis-Kir6.2ΔC26 (open circles), 6xHis-EGFP-Kir6.2ΔC26 (filled circles), and non-transfected HEK293 (filled triangles) recorded at 0 mV. Whole-cell currents were normalized using membrane capacitance to compensate for variations in cell size. Each recording represents consecutive exposures to control, 1 mM ATP, control, 10 µM thimerosal, 1 mM DTT, control, 1 mM ATP, control, and finally 100 µM tolbutamide. Arrowhead indicates zero current level, and error bars are ± SD. n = 10 for each cell type. (C) Mean currents were measured from 50 to 150 ms (dashed lines) and were plotted versus applied potential. Background current measured in transfected HEK293 cells was subtracted from mean currents, and plotted under the assumption that EK is −83 mV in the solutions used. Only −100 mV to +100 mV is presented, in +20 mV incremental steps, in the I–V relationships in (A).
