[Prepotentials of cells of the contractile myocardium]

The APs of the contractile myocardium cells were studied in heart ventricles of different animal species in hyperkalemia, ischemia, fibrillation. Prepotentials of the "step" type were shown to appear at the front of the AP increment in all cases of impaired conduction of excitation. Quantitative differences of the prepotentials were revealed in fibrillation between mammals and birds.