Creatine kinase system of one month age rats is functionally weaker then in mature animals. Increased activity of creatine kinase in the blood of one month old rats can reflect the increased permeability of mitochondrion membranes of tissue cells in comparison with mature animals.
Isoenzymes consisting of M-subunits prevail in the myocardium and skeleton muscles of one month old rats, but with age because of epigenetic transformations, the amount of H-subunits increases, which influences the direction of carbohydrate metabolism in the adult animal tissues.