Figure 6.
Cysteine-modifying agents do not disrupt the effects of reducing agents. A, Time course showing that application of NEM does not disrupt the enhancement of Cav3.2 currents by DTT. For these experiments, DTT was applied first, followed by a 1–2 min wash, NEM was then applied for 8–15 min, followed by another wash, and DTT was then applied for a second time. We then compared the magnitude of the first DTT effect with that of the second (for calculation of the second effect, we considered the steady-state inhibition by NEM as a new baseline). In similar experiments from five cells, the current enhancement from the second application of DTT was 53 ± 8% compared with 45 ± 4% for the first application, indicating no inhibition of DTT by NEM. B, In contrast, NEM significantly attenuated the inhibition by DTNB. The first application of DTNB produced an average inhibition of 48 ± 10% and the second only 22 ± 2% (n = 5; p < 0.01). C, Representative traces showing that UV light (1 s pulse) does not modify Cav3.2 currents independently or prevent subsequent modulation by DTT. In similar experiments from four cells, DTT increased currents by 48 ± 6% after exposure to UV light.