OBJECTIVETo observe the protective effect and mechanism of intermittent hypobaric hypoxia (IHH) on cardiomyocytes induced by hydrogen dioxide.

METHODSMale guinea pigs were divided randomly into two groups (n = 10): intermittent hypoxia group (IHH), and control group (non-IHH). The IHH guinea pigs were exposed to a simulated 5,000 m high altitude and hypoxia in hypobaric chamber for 28 d, 6 h/d. The control guinea pigs were kept in the same environment as IHH except hypoxia exposure. Cardiomyocytes were enzymatically isolated from left ventricle of non-CIHH or CIHH guinea pigs. The contractile was assessed in guinea pigs by a video-based motion edge-detection system. The contents and activities of malondialdehyde(MDA), lactate hydrogenase(LDH) and antioxidant enzymes were evaluated by using biochemical methods.

RESULTS1. Hydrogen peroxide could induce contractile and diastole dysfunction, the latent period was longer in IHH cardiac myocytes. 2. After hydrogen peroxide(300 micromol/L, 10 min) perfusion, LDH and MDA contents in supernatant increased significantly in non-IHH and CIHH cardiomyocytes (P < 0.01), Whereas the contents of MDA and LDH in IHH cardiomyocytes were lower than those in non-IHH cardiomyocytes (P < 0.01). 3. The activities of superoxide dismutase (SOD) and catalase (CAT) were significantly increased in the myocardium of IHH guinea pigs, after hydrogen peroxide (300 micromol/L, 10 min) perfusion, SOD and CAT activities decreased significantly in non-IHH and CIHH cardiomyocytes (P < 0.01), whereas the activities of SOD and CAT in CIHH cardiomyocytes were still higher than those in non-IHH cardiomyocytes.

CONCLUSIONIHH had a protective effect on cardiomyocytes injury induced by hydrogen peroxide, which might relate with its antioxidation effects.