Figure 2.
HO-2 regulates oxidative phosphorylation in hypoxia. (a) Hepatocyte heme oxygenase activity is not influenced significantly by hypoxia and is diminished by tin protoporphyrin (SnPP) or HO-2 siRNA. ∗P < 0.05 compared to control siRNA in 21% O2. (b) Oxygen consumption is decreased in hepatocytes under hypoxic conditions, and this is reversed by nonspecific pharmacological inhibition of HO activity or knockdown of HO-2, but not HO-1. ∗P < 0.05 compared to vehicle controls in 21% O2; #P < 0.05 compared to vehicle controls in 1% O2. (c) Hypoxyprobe staining increases with decreased availability of intracellular oxygen. Hypoxyprobe staining increases under hypoxic conditions and increases further with knockdown of HO-2 (suggesting increased cellular hypoxia). (d) Mitochondrial ROS increases under hypoxia in hepatocytes as determined by relative MitoSOX fluorescence. This is reversed by knockdown of HO-2.