[The sino-atrial node as an indicator of oscillatory processes in the cardiovascular system].
The spectrogram of heart rate in denervated (vagotomy + propranolol) and artificially ventilated cats always contains the true respiratory peak and 1-3 resonance ones pacing at intervals equivalent to frequency of breathing. Hypothermic decrease of heart rate periodically draws the splitting of respiratory peaks and generation of supplementary rate-dependent peaks reflecting the interference of heart and breathing rhythms. The functional base for detection of mentioned peaks is myogenic reaction of sino-atrial node to its extension by fluctuations of venous inflow.