FIGURE 3.

Effect of H₂O₂ on whole-cell currents (A and B, whole-cell patch) and single channel currents (C–F, cell-attached patch) in TRPC6-expressing HEK293T cells. A, representative whole-cell current measurements obtained by a Gap-free protocol in a Mock (open circles)- and a TRPC6-transfected (solid circles) cell at a holding potential of −60 mV. The dashed lines indicate zero currents. Application and removal of H₂O₂ are indicated by the vertical lines. B, summary data, showing the H₂O₂ effect on the whole-cell currents in the Mock control and TRPC6-expressing cells. The responses were measured by the difference between the membrane current before application of H₂O₂ and the peak current after application of H₂O₂. The whole-cell currents are expressed as current density (pA/pF), normalized to the cell membrane capacitance. n indicates the number of cells analyzed. Asterisk indicates statistically significant difference compared with Mock (Student's t test). C, representative traces of single channel currents in a cell-attached patch. Left panel, a real time continuous recording. The arrowhead indicates the closed state of the channels. Downward deflections indicate inward currents. Right panel, the time-expanded portions of the selected regions in the upper trace, indicated by a (Pre-H₂O₂) and b (Post-H₂O₂). D, amplitude histograms (upper panels) and open time distributions (bottom panels) of the currents before (left panels) and after (right panels) application of H₂O₂ in the traces shown in C. The amplitude histograms were fitted to Gaussian function. M in the bottom panels indicates mean open time. E, single channel amplitudes before and after application of 10 μm H₂O₂. n indicates the number of cells analyzed. F, effect of H₂O₂ on the NP_o of TRPC6 channels in 12 cells. *, p < 0.05, compared with pre-H₂O₂ (paired Student's t test). The cells in each group of B, E, and F were from at least four sets of transfection.