[Changes in calcium uptake and Ca(2+)-ATPase activity of cardiac sarcoplasmic reticulum in rat associated with hypoxia of various degrees].

Two groups of Wistar rats were exposed to hypoxia at 5000 to 8000 m high above the sea level in a hypobaric chamber for 7 days. The effects of hypoxia on left cardiac function, sarcoplasmic reticulum (SR) Ca2+ ATPase activity and SR calcium uptake were observed. The results indicated that the left ventricular function exposed to hypoxia at 5000 m was much higher than that at 8000 m. Calcium uptake and Ca2+ ATPase activity of the exposed groups decreased significantly compared with those of the control group, but they were much higher in the exposed group at 5000 m than at 8000 m. These results suggest that the changes in calcium uptake and Ca2+ ATPase activity of SR may be one of the important biochemical indicators for cardiac function alterations associated with hypoxia.