FIGURE 7. The inhibitory effect of AngII on ROMK channel activity is mediated, in part, by NADPH oxidase.

A, pretreatment of CCDs from LK rats with one of two NADPH oxidase inhibitors, IDP (10 μM) or apocynin (100 nM), blocked the effect of AngII on the ROMK channel. Neither one of these inhibitors had a significant effect on base-line channel activity. CCDs pretreated with IDP failed to respond to PMA with an inhibition of ROMK channel activity, suggesting that AngII inhibits the channel via the activation of the PKC-NADPH oxidase pathway. B, relative expression of mRNA encoding p22^phox and p47^phox in CCDs from NK- and LK-fed rats. Dietary potassium restriction for 4 – 6 days increased expression of p47^phox (but not p22^phox) when compared with NK-fed rats.