The main aim was to find out whether long-lasting stepwise exposure to extreme hypoxia affects left ventricular (LV) geometry and systolic function. Adult male rats were exposed to intermittent hypobaric hypoxia (8 h/day) with increasing altitude in steps of 1000 m every 3 weeks up to 8000 m. While the LV cavity diastolic diameter did not change over the whole range of hypoxia, the wall thickness increased significantly at the altitude of 8000 m. LV fractional shortening ranged between 48.1 % and 50.1 % and remained unaffected even at the most severe hypoxia. At the end of experiment, haematocrit reached 83 %, mean systemic arterial pressure 120 % and relative LV weight 154 % of normoxic values while RV systolic pressure and relative RV weight doubled. Myocyte hypertrophy and myocardial fibrosis were more pronounced in RV than in LV. In conclusion, LV systolic function was preserved after chronic stepwise exposure of rats to extreme intermittent hypoxia despite moderate concentric hypertrophy and myocardial remodelling.

主要目的是找出长期逐步暴露于极度缺氧是否会影响左心室 (LV) 几何形状和收缩功能。成年雄性大鼠暴露于间歇性低压缺氧（8 小时/天），每 3 周以 1000 m 的步长增加海拔至 8000 m。虽然在整个缺氧范围内 LV 腔舒张直径没有变化，但在海拔 8000 m 处壁厚显着增加。LV 缩短的分数介于 48.1% 和 50.1% 之间，即使在最严重的缺氧情况下也不受影响。在实验结束时，血细胞比容达到正常值的 83%，平均全身动脉压为 120%，相对 LV 重量为常氧值的 154%，而 RV 收缩压和相对 RV 重量加倍。RV 中的心肌细胞肥大和心肌纤维化比 LV 更明显。综上所述，