[Changes in the activity of the intracardiac postganglionic apparatus during the interaction of the regulatory sympathetic and parasympathetic effects on the pacemaker rhythm].

Chronotropic effect on the isolated sinus node of the frog heart and postganglionic impulse activity of the intracardiac pathways were studied during separate and joint stimulation of extracardiac sympathetic and parasympathetic nerves. The joint stimulation attenuated or augmented the impulse activity. This effect depended on the "energy" of initial parasympathetic and/or sympathetic activity. beta-Adrenoblocking inderal abolished the parasympathetic impulse activity augmentation. A possible role of intracardiac ganglionic system in the sympathetic-parasympathetic interaction is discussed.