Figure 1. Effects of amiloride and NPPB on hyposmolality-induced I_sc and conductance.

A, I_sc increased gradually with time after exposure of cells to a hyposmotic solution. a, amiloride (10 μM) applied to the apical solution abolished the increased I_sc. b, NPPB (100 μM) applied to the apical and basolateral solutions also abolished the increased I_sc, reducing it to a level similar to that with amiloride. B, conductances did not significantly change during the period when cells were exposed to a hyposmotic solution. a, amiloride (10 μM) applied to the apical solution induced a small decrease in conductance. b, NPPB (100 μM) applied to the apical and basolateral solutions induced a much larger decrease in conductance than amiloride. Although the I_sc increased with time after application of hypotonicity, the conductance did not significantly increase. The amiloride-sensitive conductance might increase, but the amiloride-sensitive conductance was much smaller than the total conductance (Fig. 1B a). Therefore, we could not see a significant increase in the total conductance even if the amiloride-sensitive conductance increases. Number of experiments (n) = 4.