HMOX2 and hypertensive disorder: HO-2 knockout mice exhibit more abundant CSE-derived H2S in carotid bodies and enhanced carotid body chemosensitivity, and CSE inhibitors prevent OSAS in HO-2 knockout mice.288 The carotid body of IH-exposed rats showed reduced CO levels, PKG activity, and CSE phosphorylation, whereas all of these effects were abolished after administration of the membrane-permeable ROS scavenger MnTMPyP.287 Therefore, we hypothesized that the activation of H2S signaling in the carotid body under IH is also a key trigger of sympathetic activation and hypertension (Fig. 3 8).