[Evaluation of the degree of genetically determined reactions of the human cardiorespiratory system to hypoxia and hypercapnia].

Using the twin method (16 pairs of monozygotic and 14 pairs of dizygotic twins), the role of the genotype and environment in the phenotypical variations of cardiorespiratory reactions to increasing hypoxia and hypercapnia was investigated. The process of emergency adaptation to acute hypoxia was shown to be associated with both genetically determined potentialities and acquired abilities. It is suggested that regular training may change sensitivity and emergency mechanisms of adaptation to hypoxia. However, the level of these changes depends on the individual genotype. The variability of hypercapnia sensitivity which is an individual genetically determined constant appears to be very low.