[Effect of the rest interval on the contractile activity of the myocardium].

Isolated strips of the heart auricles and ventricles of frogs at high stimulation frequencies revealed rest potentiation which depended both on the stimulation rhythm and on the duration of rest interval. Amphibians as well as warm-blooded animals and fish seem to display a possibility of Ca++ entering a cell during the period of rest via non-electrogenic calcium canals, but in amphibians this mechanism of the myocardium activation is compansatory, rather.