[The cardioprotection of intermittent hypoxic adaptation]

Intermittent hypoxia (IH), or periodic hypoxia is referred as exposure to hypoxia interrupted by normoxia that occurs under many physiological and pathophysiological conditions. A lot of researches showed that IH adaptation, like ischemic preconditioning (IPC) and long-term high-altitude hypoxic adaptation (LHA), had significant cardioprotective effects including increasing the tolerance of myocardium to ischemia/reperfusion injury, limiting infarction size and morphologic damage, inhibiting apoptosis of myocardial cells, enhancing recovery of cardiac function in ischemia/reperfusion, and antiarrhythmia. However, the precise mechanisms underlying the protective effects of IH against ischemia/reperfusion injury are far from clear. The potential candidates participating in the protective effects of IH include oxygen transport, energy metabolism, neurohumoral regulation, antioxidase, stress protein, adenosine, ATP-sensitive potassium channel, mitochondrion, calcium control, nitric oxide and protein kinase. The effects of IH are affected by the protocol of hypoxic exposure, age and sex of experimental animals. IH adaptation, for longer lasting time than IPC and lesser side effect than LHA, might have a practical value for using.