0111 : Role of endoplasmic reticulum stress in the deleterious cardiovascular consequences of chronic intermittent hypoxia. Beneficial effects of high-intensity interval training

Background Chronic intermittent hypoxia (IH) is described as the major detrimental factor leading to cardiovascular morbi-mortality in obstructive sleep apnea (OSA) patients. Previous animal studies demonstrated that IH increases myocardial susceptibility to ischemia-reperfusion (IR). Among mechanisms involved in the pathophysiology of IR, modulation of endoplasmic reticulum (ER) stress seems to play a major role. Exercise is known to exert beneficial effects on the cardiovascular system and a growing body of evidence demonstrates a particular efficiency of high-intensity interval training (HIT). The aim of the present study was 1) to evaluate the effects of HIT on IH-induced increased susceptibility to IR; 2) to determine whether ER stress was involved. Methods Wistar male rats were exposed to 21 days of IH (21-5% FiO2, 60s cycle, 8h/day) or normoxia (N). After one week of IH alone, rats were daily submitted to both IH and HIT (2*24min, 15 to 30m/min). Rat hearts were either submitted to an IR protocol ex-vivo (30min-global ischemia followed by 120 min-reperfusion, Langendorff technic) or rapidly frozen to evaluate ER stress by Western Blot. Results IH induced a significant increase in infarct size (35.4±3.2% vs 22.7±1.7% of ventricles, in IH and N respectively, p Conclusion These findings show that HIT prevented the IH-dependent increased in myocardial susceptibility to IR, probably through a down-regulation of proapoptotic ER stress pathway. HIT could represent a good preventive strategy to limit myocardial ischemia reperfusion-related damages in OSA patients.