Table 2.

Relevant in vitro and in vivo models of chronic and chronic intermittent hypoxia.

System	Model	Details of model	References
in vitro	Cells cultured in hypoxic chambers	Constant hypoxia achieved using high levels of nitrogen. Range oxygen concentrations can be used, 1% most common. Wide range of timeframes.	(64, 65)
	Cells treated with cobalt chloride	Model of HIF activation similar to constant hypoxia. Cellular response sometimes differs from true hypoxia.	(65, 66)
	Cells cultured in hypoxic chambers with cycling oxygen levels	Models CIH in vitro. Wide range of oxygen levels at nadir and cycle patterns in use.	(65)
in vivo	Rodents in hypoxic chambers	Constant hypoxia achieved using high levels of nitrogen. Range of oxygen concentrations in use.	(67, 68)
	Rodents in hypoxic chambers with cycling oxygen levels	Chronic intermittent hypoxia to model OSA. Oxygen cycles often applied only during sleeping hours of rodents. Wide range of oxygen levels at nadir and cycle patterns in use.	(39, 69)
	Rodents injected with sodium nitrite	Chronic intermittent hypoxemia through methemoglobinemia.	(70, 71)