[Changes in the lungs and the mass of the right ventricle of the heart in chronic hypoxia (experimental-morphological study)].

In experiments on 105 white rats using histological, histochemical, and morphometric methods the state of the lungs following daily "rises" in a pressure chamber to the "hight" of 5000--9000 m at verious time intervals--from 1 day to 9 weeks was studied. In 18 animals "ascents" were preceded by sinistral pulmonectomy. In parallel, the heart was investigated by the method of separate weighing. At initial stages changes in the lungs were characterized predominantly by impairment of the blood- and lymphocirculation. Subsequently, disorders of the microcirculation were observed to diminish and compensatory-hypertrophic changes in the lung tissue and vessels were noted. As the effect of hypoxia continued, sclerotic processes appeared, and extensive focal emphysema developed. These changes were manifested in a greater degree and appeared sooner with an increase in the extent of rarification of the atmosphere. Possibilities for adaptation to hypoxia in animals with the one lung were considerably lower as compared with normal ones. Hypercapnia produced an effect similar to that of hypoxia, making its influence on the structural elements of the lungs graver. Prolonged hypoxia led to hypertrophy of the right ventricle of the heart; the main factor in development of which the authors considered the elevation of the tonus and subsequent structural rearrangement of small vessels in the form of myoelastosis and myoelastofibrosis of the walls with narrowing of the lumen.