title: [Comparative characteristics of the mechanical activity of atria and ventricles].
abstract: Differences between parameters of isometric and isotonic contractions of atria and ventricles were studied in warm-blooded and cold-blooded animals. The maximal shortening velocity of contractile element was determined from isometric contraction using a two-component Hill's model as well as from the strength-velocity ratio. The atrial Vmax was about twice as high as that of ventricles. The rate constant of delayed activation in atrium was 10.6 +/- 0.4 s-1, in the rabbit ventricles 4.42 +/- 0.60 s-1. The data suggest differences of ATP hydrolysis velocity with actomyosin ATP-ase of atrium and ventricles.
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D000818:Animals; D016275:Atrial Function; D006321:Heart / Q000502:physiology*; D007537:Isometric Contraction; D007551:Isotonic Contraction; D009200:Myocardial Contraction; D009206:Myocardium / Q000201:enzymology; D009210:Myofibrils / Q000201:enzymology; D011817:Rabbits; D011898:Ranidae; D051381:Rats; D014426:Turtles; D016276:Ventricular Function
chemical_list: D000251:Adenosine Triphosphatases
vernacular_title: Sravnitel'naia kharakteristika mekhanicheskoĭ aktivnosti predserdiĭ i zheludochkov.