THE PHYSIOLOGICAL AND ANATOMICAL DEMONSTRATION OF FUNCTIONALLY SELECTIVE PARASYMPATHETIC GANGLIA LOCATED IN DISCRETE FAT PADS ON THE FELINEMYOCARDIUM

Experiments utilizing surgical parasympathectomy of discrete fat pad g anglia on the surface of the heart have suggested that there are two a natomically segregated and physiologically independent parasympathetic intracardiac ganglia which are capable of selective control of sino-a trial (SA) rate and atrio-ventricular (AV) conduction. Some pharmacolo gical data, however, are inconsistent with these conclusions. We have examined the cardiodynamic effects of discrete injections of a ganglio nic blocking drug into two fat pads on the surface of the cat heart. T hese fat pads were shown to contain ganglion cells histologically. It was observed that vagal effects upon cardiac rate are selectively medi ated by neurons located in ganglia overlying the right pulmonary veins at the junction of the right atrium and superior vena cava. On the ot her hand, vagal effects upon AV conduction were selectively mediated b y neurons located in a fat pad at the junction of the inferior vena ca va and the inferior left atrium. These pharmacological data support th e concept that specific intracardiac ganglia are capable of selective control of SA rate and AV conduction.