FIG. 1.

H₂S-induced Na⁺/K⁺-ATPase endocytosis and activity inhibition in renal tubular epithelial cells. (A, B) Cells were treated with 25 μM NaHS for different durations (A) and with different concentrations of NaHS for 60 min (B) inhibited Na⁺/K⁺-ATPase activity. (C, D) NaHS caused a decrease in Na⁺/K⁺-ATPase activity in membrane fractions at different concentrations of NaHS for 60 min (C) and had no effect in the cytoplasm fraction (D). (E–G) Isolated cell membrane (E) and cytoplasm (F) through labeling of cell surface by biotinylation and, respectively, detected the expressions of Na⁺/K⁺-ATPase α1 and β1 subunit by western blot analysis, and calculated Na⁺/K⁺-ATPase membrane-to-cytoplasm ratio (G). (H, I) H₂S had no effect on Na⁺/K⁺-ATPase α1 (H) and β1 (I) subunit expression after treatment with different concentrations of NaHS for 60 min and with 25 μM NaHS for different durations. Data in the graphs are means±SEM. H₂S, hydrogen sulfide; Na⁺/K⁺-ATPase inhibitor, a positive control; Oua, ouabain. See also Supplementary Figures S1 and S2.