Effect of adaptation to continuous and intermittent hypoxia on heart resistance to ischemic and reperfusion arrhythmias

: The effect of adaptation to intermittent hypoxia in a pressure chamber (5.000 m daily for 6 hours for 30 days) on arrhythmias occurring in occlusion of the coronary artery and subsequent reperfusion in rats was compared with the effect of adaptation to continuous hypoxia at middle-mountain altitudes. Adaptation to intermittent hypoxia reduced the duration of severe ventricular arrhythmias in acute ischemia and reperfusion to a great measure. Adaptation to continuous hypoxia at middle-mountain altitudes has a similar effect only in ischemic arrhythmias but at the same time promotes the development of reperfusion arrhythmias. The possible mechanisms of these effects are discussed.