[Mechanism of increasing the functional capacity of the cardiac muscle after adaptation to physical exertion].
The main parameters of contraction and relaxation of papillary muscle strips taken from the left ventricle of control and exercise-adapted rats were measured. The contractile velocity and amplitude of thin and thick strips of the cardiac muscle of adapted rats were found to be 2--3 times higher than in the controls. This fact can be explained by an elevation of myosine ATP-ase activity. The developed tension was higher than in the controls only in thick strips of adapted rats. This increase depends on the adaptive augmentation of the functional power of systems responsible for the transport of oxygen and substrates to the mitochondria. The myocardium of adapted rats differed from that of the controls in that the relaxation velocity and compliance were significantly elevated. These facts suggested an increase in the funcitonal power of the ionic transport system that is responsible for Ca++ elimination from the myofibrils. In general, the results suggest that an elevation of maximal myocardial performance after adaptation to exercises may be due to a coordinative increase in the power of three basic systems of the myocardial cells--ion transport system, myosine ATPase and resynthesis ATP system.
D000222:Adaptation, Physiological; D000251:Adenosine Triphosphatases / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000096:biosynthesis; D000818:Animals; D002118:Calcium / Q000378:metabolism; D004734:Energy Metabolism; D006321:Heart / Q000502:physiology*; D006339:Heart Rate; D008297:Male; D009200:Myocardial Contraction; D009206:Myocardium / Q000166:cytology; D009210:Myofibrils / Q000378:metabolism; D005082:Physical Exertion; D051381:Rats
D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases; D002118:Calcium
O mekhanizme uvelicheniia funktsional'nykh vozmozhnosteĭ serdechnoĭ myshtsy pri adaptatsii k fizicheskoi nagruzke