Izakov V Ia, Zhelamskiĭ S V
Fiziol Zh SSSR Im I M Sechenova. 1984 Oct;70(10):1429-35.
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.
