Fig. 2.

Replacement of H₂S normalizes mitochondrial oxidant production and protects against mitochondrial depolarization in endothelial cells placed in high extracellular glucose. Mitochondrial ROS production was measured in low (5.5 mM, LG) or high (40 mM, HG) glucose conditions at 7 d by using the MitoSOX red method. A shows the responses to H₂S (100–300 μM) in no glucose, high glucose, and alternating high/low extracellular glucose conditions (H/L). H₂S afforded a concentration-dependent and significant suppression of MitoSOX oxidation (^#P < 0.05). The Western blot Inset in A shows that the expression of the H₂S-generating enzyme CSE was not suppressed by high glucose. B shows representative flow cytometric and fluorescent microscopic images for the four respective groups (low and high glucose with and without 300 μM H₂S). C shows the oxidation of JC-1, a dye used to detect mitochondrial membrane depolarization. In cells placed in high glucose, there was an increase in mitochondrial depolarization (*P < 0.05), which was attenuated by H₂S (P < 0.05) (n = 5).