Direct and indirect effects of intermittent hypoxia (IH) on the chemo-reflex pathway including the carotid body (the sensor), neurons of nucleus of the tractus solitarious (nTS) and rostral ventrolateral medulla (RVLM) and adrenal medulla (sympathetic end organ). HIF-1 and HIF-2= Hypoxia-inducible factors 1 and 2, POE= pro-oxidant enzymes, AOE= anti-oxidant enzymes, ROS= reactive oxygen species, mAChR= muscarinic acetylcholine receptor, CA secretion= catecholamine secretion, CSN= carotid sinus nerve.