Hydrogen Sulfide Prevents Hydrogen Peroxide-Induced Activation of Epithelial Sodium Channel through a PTEN/PI(3,4,5)P(3) Dependent Pathway

Sodium reabsorption through the epithelial sodium channel (ENaC) at the distal segment of the kidney plays an important role in salt-sensitive hypertension. We reported previously that hydrogen peroxide (H(2)O(2)) stimulates ENaC in A6 distal nephron cells via elevation of phosphatidylinositol 3,4,5-trisphosphate (PI(3,4,5)P(3)) in the apical membrane. Here we report that H(2)S can antagonize H(2)O(2)-induced activation of ENaC in A6 cells. Our cell-attached patch-clamp data show that ENaC open probability (P(O)) was significantly increased by exogenous H(2)O(2), which is consistent with our previous finding. The aberrant activation of ENaC induced by exogenous H(2)O(2) was completely abolished by H(2)S (0.1 mM NaHS). Pre-treatment of A6 cells with H(2)S slightly decreased ENaC P(O); however, in these cells H(2)O(2) failed to elevate ENaC P(O). Confocal microscopy data show that application of exogenous H(2)O(2) to A6 cells significantly increased intracellular reactive oxygen species (ROS) level and induced accumulation of PI(3,4,5)P(3) in the apical compartment of the cell membrane. These effects of exogenous H(2)O(2) on intracellular ROS levels and on apical PI(3,4,5)P(3) levels were almost completely abolished by treatment of A6 cells with H(2)S. In addition, H(2)S significantly inhibited H(2)O(2)-induced oxidative inactivation of the tumor suppressor phosphatase and tensin homolog (PTEN) which is a negative regulator of PI(3,4,5)P(3.) Moreover, BPV((pic)), a specific inhibitor of PTEN, elevated PI(3,4,5)P(3) and ENaC activity in a manner similar to that of H(2)O(2) in A6 cells. Our data show, for the first time, that H(2)S prevents H(2)O(2)-induced activation of ENaC through a PTEN-PI(3,4,5)P(3) dependent pathway.