Postnatal development in intermittent hypoxia enhances resistance to myocardial ischemia/reperfusion in male rats.
To assess the tolerance of rats that developed from birth in intermittent hypoxia (IH) to myocardial ischemia and reperfusion, we set up a reproducible model in our laboratory. IH rats were raised 60 days from birth in a hypobaric chamber at 5000 m for 6 h daily, while controls were in continuous normoxic conditions. At 60 days after birth, the antioxidant capacity of the heart was determined; arterial and venous partial pressures of oxygen were measured at sea level and 5000 m altitude. In addition, isolated hearts of each group were perfused in Langendorff mode and submitted to 30 min global ischemia followed by 30 min reperfusion to compare functional recovery and lactate dehydrogenase release. For the IH rats, recovery of left ventricular developed pressure (DP), the maximum of the positive or negative first derivative of left ventricular pressure with respect to time (+/-LV d P/d t), end-diastolic pressure (EDP), and pressure-rate product (PRP) were all superior ( P<0.05) to those of control rats. The myocardial antioxidant capacity was also significantly increased in the left ventricle of IH rats. Further, at 5000 m altitude the arterio-venous oxygen gradient ( Pa-vO(2)) was significantly ( P<0.01) higher in the IH rats than in the controls. These data indicate that IH from birth enhances the tolerance of the heart to ischemia/reperfusion, elevates the myocardial antioxidant capacity, and increases oxygen extraction.
Physiological Laboratory of Hypoxia, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 320 Yue Yang Road, 200031 Shanghai, China.
Wei-Zhong
WZ
Zhu
Jian-Wen
JW
Dong
Hai-Lei
HL
Ding
Huang-Tian
HT
Yang
Zhao-Nian
ZN
Zhou
D000222:Adaptation, Physiological; D000375:Aging / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn; D000975:Antioxidants / Q000032:analysis; D001835:Body Weight; D005247:Feeding Behavior; D005260:Female; D000860:Hypoxia / Q000150:complications / Q000503:physiopathology*; D007113:Immunity, Innate / Q000502:physiology*; D008297:Male; D010088:Oxidoreductases / Q000097:blood*; D011247:Pregnancy; D051381:Rats; D017207:Rats, Sprague-Dawley; D020127:Recovery of Function / Q000502:physiology*; D015427:Reperfusion Injury / Q000150:complications / Q000503:physiopathology* / Q000517:prevention & control; D018487:Ventricular Dysfunction, Left / Q000150:complications / Q000503:physiopathology*
D000975:Antioxidants; D010088:Oxidoreductases