Effects Of Hypoxia On Cardiac Function And Its Mechanisms

The effects of hypoxia on cardiac function have been an important question in clinical medicine, high mountain medicine and aerospace medicine. Up to now, the effects of hypoxia on left and right cardiac function have been reported by many researchers, but there are few studys on the mechanisms of altered cardiac function induced by hypoxia.In the present study, the effects of hypoxia on changes of hemodynamics and cardiac hypertrophy, variations in ventricular myofibrillar Ca²⁺,Mg²⁺ -ATPase activity, sarcoplasmic reticulum (SR) ATPase activity and SR Ca²⁺ uptake ability, and the myocardium contractile protein β-MHC gene and SR Ca²⁺ -ATPase gene expressions were examined.Male adult Wistar rats were divided randomly into simulatng 5000m hypoxia for 1, 2 and 4 weeks, 8000m hypoxia for 1 week, hypoxic acclimatization and normoxic restoration groups. For the hypoxic acclimatization group, the rats were gradually acclimatized to the altitude by first exposing the rats at a height of 2000m above sea level for 4 days, and then returned to sea level and remained there for 4 days, secondly exposing them at 4000m above sea level for 4 days and returned to sea level and remained there for 4 days again, and lastly exposing them at 8000m above sea level for 7 days, for the normoxic restoration group the rats were exposed to 8000m hypoxia in a hypobaric chamber for 1 week, and then placed in air for 1 and 2 weeks, and those stayed in the lab without any treatment being as the controls.The results were as follows. The survival rates of animals...