CHRONOTROPIC AND VAGAL-BLOCKING EFFECTS OF DCI STUDIED BY DIRECT PERFUSION OF THE SINUS NODE

¹ Section on Cardiovascular Research, Henry Ford Hospital, Detroit, Michigan

DCI studied by direct perfusion into the canine sinus node through its own artery has three effects on the node. First, in low concentrations it has a slight positive chronotropie effect but in higher concentrations has a negative chronotropic effect. Second, in moderate and higher concentrations DCI blocks the acceleration from adrenergic stimuli. The third effect is an associated blockade of vagal stimuli as well as of directly perfused acetylcholine, both occurring only with higher concentrations of intranodal DCI.