[Intensity of RNA synthesis and the DNA content in the myocardium of newborn rats during adaptation to altitude hypoxia].

Newborn rats were exposed to staged adaptation to altitude hypoxia in a pressure chamber at an atmospheric pressure corresponding to an altitude from 2000 to 9000 m. The time course of changes in the synthesis of RNA and DNA by the nuclei of muscle and connective tissue cells of the heart were studied by light autoradiography with the use of 3H-5-uridine and 3H-thymidine. In the course of early postnatal ontogenesis adaptation to altitude hypoxia was demonstrated to be accompanied by the intensified synthesis of nucleic acids by muscle and non-muscle cells of the heart, which is regarded as a compensatory-adaptation reaction of the myocardium to hyperfunction under the test experimental conditions.