[Lactate dehydrogenase isoenzyme spectrum in the myocardium and skeletal muscles of animals under physical stress].

Single physical load (forced run up to fatigue) changes the lactate dehydrogenase activity in the myocardium and skeletal muscles of rats. It is pronounced in a sharp rise of the activity 1 h after the action, in a decrease 6 h after and again in an increase a day later and a gradual fall on the third seventh days. An increase in the portion of isoenzymes typical of the anaerobic metabolism is peculiar to the myocardium and skeletal muscles, that finds its manifestation in both an increase in the lactic acid amount and the lactate/pyruvate coefficient. A regular rise in the LDH2 amount in all periods of the study and LDH5 in the early period after the action is peculiar to the myocardium and the increase in the LDH5 content is characteristic of the skeletal muscles.