PHYSIOLOGICAL CHARACTERISTICS OF HIGH-ALTITUDE ADAPTED ANIMALS

蓝羊、鼠兔和牦牛生活在海拔6100米的西藏高原，是世界哺乳动物中适应高海拔的典型动物。这些动物在高海拔地区居住的历史很长，由于它们的生理和形态特征很好地适应了高海拔环境，被认为是“完全适应高海拔地区的动物”。为探讨青海蓝羊高原适应的生理特点，对海拔3750m的青海省中国羊进行了肺血流动力学的测定。主要测量指标为体重(BW)、体动脉压(PSA)、肺动脉压(PPA)、红细胞压积(Ht)、左室重(LVW)、右室重(RVW)和血气分析。本研究的主要发现是：1)与猪相比，蓝羊的右室肥厚指数(RVW/LVW)和氧耗量(VO2)显著减小；2)两种羊的右室负荷指标PPA/PSA均随海拔升高而增加，但蓝羊的增加幅度较小。根据这些观察，小Ht和RVW/LVW被认为是完全适应高海拔动物的特征，如鼠兔。

The blue sheep as well as pika, and yak live in the Tibetan highlands to an altitude of 6,100 m and are typical animals adapted to high altitude among mammals of the world. These animals have a long history of habitation at high altitude and are considered to be "animals completely adapted to high altitude" because of their physiologic and morphological traits well-adapted to high-altitude environments. To evaluate physiologic characteristics of high-altitude adaptation of the blue sheep, changes in the pulmonary hemodynamics were examined in Qinghai Province, China (altitude 3,750 m). Primary items of measurement were the body weight (BW), systemic arterial pressure (Psa), pulmonary artery pressure (Ppa), hematocrit (Ht), left ventricular weight (LVW), right ventricular weight (RVW), and the blood gas profile. The principal finding of this study are: 1) Ht, at index of right ventricular hypertrophy (RVW/LVW), and oxygen consumption (VO2) were significantly smaller in the blue sheep compared with the pigs; 2) Ppa/Psa, an index of the right ventricular load, increased with the altitude in both species, but the increases were smaller in the blue sheep. From these observations, small Ht and RVW/LVW are considered to be characteristics of animals completely adapted to high altitude such as the pika.