[Role of carbon dioxide in the maintenance of positive changes in myocardial metabolism and the mechanisms of cardiac regulation after physical exercise training].

Four-percent carbon dioxide added to the gaseous medium during swimming exercise under normoxia increased animals' working capacity, myocardial contractility, the stability of myocardial acetylcholine store and cardiac choline reactivity, and contributed to post-exercise retention of those changes. Three months' training under the same conditions caused no further increment in adaptation parameters, while potentialities of the parasympathetic regulation mechanism even declined, and the acquired changes were promptly lost upon discontinuation of exercise. Mechanisms of action and significance of carbon dioxide in the formation of adaptation and after-effect circulatory stability are discussed.