Figure 5.

Effects of redox modulation in the hypoxic response of Kv4.2+β. (A) Effect of DTT. Peak-current amplitude to three different depolarizing voltages was measured every 5 s and plotted against time. N₂-equilibrated solutions were applied when indicated, before and after the application of 2 mM DTT for 3 min (hatched bar). In this cell, hypoxic inhibition at +40 mV was 12%, and DTT inhibition was 25%. After DTT, hypoxia produced a 1% inhibition of the current amplitude. (Right) The averaged values (mean ± SEM) of hypoxic inhibition of the currents before (open bar) and after (hatched bar) treatment with 2 mM DTT obtained in five similar experiments, and represented as in Fig. 4. (B) Effect of DTDP. A protocol similar to the one described in A was applied, but using 100 μM DTDP. In this cell, hypoxic inhibition of the peak current amplitude at +40 mV before and after treatment with DTDP amounted to 18 and 22%, respectively, and DTDP produced a 6% increase of the current amplitude. Averaged data of the effect of hypoxia before (open bar) and after (solid bar) DTDP application are represented on the right (mean ± SEM, n = 6).