Activity of in Vivo Atrial and Ventricular Neurons in Chronically Decentralized Canine Hearts

The spontaneous activity of 175 neurons located in the ventral right atrial and ventral interventricular ganglionated plexi was recorded in eight anesthetized dogs, the hearts of which were chronically decentralized at least 2 wk before recordings were made. Ganglia were subsequently identified anatomically in the immediate vicinity of the recording sites. Spontaneous activity was correlated with the cardiac cycle in 57% of the atrial and 62% of the ventricular neurons and with the respiratory cycle in 29% of the atrial and 28% of the ventricular neurons. Spontaneous cardiovascular-related activity was recorded when systemic arterial pressure was between 80 and 175 mmHg. The activity of 23 atrial and 15 ventricular neurons was altered when discrete regions of the heart were mechanically distorted by gentle touch. These data imply that cardiac ganglionated plexi contain afferent neurons that receive inputs from limited regions of the heart. The spontaneous activity generated by intracardiac neurons was not altered when extracardiac tissues were distorted. These results demonstrate that neurons in ganglia on chronically decentralized hearts can generate spontaneous activity, a large fraction of which is correlated with cardiovascular or respiratory events.