FIGURE 2.

Effect of H₂O₂ on the intracellular Ca²⁺ signal in TRPC6-expressing and empty vector-transfected HEK293T cells. A, representative traces, showing the changes in intracellular Ca²⁺ level upon 5 mm Ca²⁺ readdition to a Ca²⁺ free bathing solution in cells treated with different concentrations of H₂O₂. The Ca²⁺ concentration in the bathing solution is indicated by the numbers inside the top open bar. Application of H₂O₂ is indicated by the top solid bar. [Ca²⁺]_B indicates the Ca²⁺ concentration in the bathing solution. The numbers next to each trace indicate the concentration of H₂O₂ (μm) applied. B, representative traces, displaying intracellular Ca²⁺ response to Ca²⁺ readdition in vector-transfected (Mock) and rTRPC6-transfected (TRPC6) cells in the presence of 10 μm H₂O₂. The Ca²⁺ concentration in the bathing solution is indicated by the numbers inside the top open bar. Application of H₂O₂ is indicated by the top solid bar. [Ca²⁺]_B indicates the Ca²⁺ concentration in the bathing solution. C, summary data from five sets of TRPC6-transfected cells and two sets of empty vector-transfected cells, showing a dose-dependent response of Ca²⁺ entry on H₂O₂ treatments in TRPC6-expressing but not in vector-transfected cells. Δ340:380 ratio indicates the difference in the values before addition and the peak values after addition of 5 mm Ca²⁺ solution, representing the Ca²⁺ entry response. The numbers of cells in each group are from 16 to 25. *, p < 0.05, compared with 10⁻⁸ m in TRPC6-transfected cells; †, p < 0.05, comparison between TRPC6-transfected and Mock-transfected cells at corresponding doses. D, percent increases in the ratios of 340:380 in response to 10 μm H₂O₂ in Mock- and TRPC6-transfected cells. n indicates the number of cells analyzed. *, p < 0.05, TRPC6 versus Mock.