[The "staircase" phenomenon in the myocardial activity of fishes and amphibians].

Studies have been made on chrono- and inotropic effects in the heart of the frog Rana temporaria and fishes Silurus glanis and Cyprinus carpio during stationary and transitional stimulation. In contrast to data in the literature, no interspecific differences were found in changes of the amplitude of cardiac contractions induced by changes in rhythmic stimulation.