Denervation of the heart (bilateral vagotomy and propranolol) in artificially ventilated cats didn't remove respiratory peaks on the spectrogram of heart rate, while burst stimulation of vagus nerve increased or decreased them several times by synchronization of the heart and vagus rhythms, which in its turn was observed under the bradycardia only. At the… (More)
In cats, magnesium, potassium and finoptin diminished the vagal chronotropic effect whereas calcium potentiated it. In potassium chloride administration, the vagotropic action was due to a selective diminishing of the tonic component.
The effect of met- and leu-enkephalins in cats was characterised by depressing vagotropic action due to a selective decrease in the tonic component. The potentiation of synchronizing actions may serve as an index of a reliable and stable mechanism of the beat-by-beat control of the cardiac rhythm.
In experiments on frogs, rats, rabbits, cats, dogs and simians the synchronization of cardiac and vagal rhythms was achieved during stimulation of vagus nerve. The relative bounds of the synchronization ranges were not dependent on the species of animal or level of sympathetic activity. In this connection, the whole variety of the cardiochronotropic… (More)
Burst vagus stimulation led to synchronization of the cardiac and vagal rhythms at certain frequency ranges. The increase of the number of impulses in a burst from 1 to 16 extended the range of synchronization and shifted it towards lower frequencies forming a total range of exact regulation of the heart rate within 85--40% of the initial rate. It was… (More)