Abstract
When the animals are exposed to high-altitude over a long period, the pulmonary hypertension and right ventricular hypertrophy are observed. These responses are typical singes for the adaptation to high-altitude. Main factors for affecting to living body are hypoxia and cold in the high-altitude. These two factors affect to the lung and blood sides. In the lung side, the pulmonary capillaries constrict due to hypoxia. Its call hypoxic pulmonary vasoconstriction or HPV. In the blood side, RBC and Ht increase by exposure to high-altitude and it cause increasing blood viscosity. These two factors, increased HPV and blood viscosity, are very important to cause the pulmonary hypertension or right ventricular hypertrophy. The pika, blue sheep, and yak are living in the Tibetan Highlands to an altitude of 6100m above sea level and are typical animals adapted to high-altitude among mammals of the world. These mammals have a long history of habitation at high-altitude and are considered to be animals completely adapted to high altitude. The purpose of this study is to make clear the physiological characteristics of pika, blue-sheep, and yak as high-altitude adapted animals. [Jpn J Physiol 55 Suppl:S65 (2005)]
