Coronary Inflow and Oxygen Usage Following Cardiac Sympathetic Nerve Stimulation in Unanesthetized Dogs

The effects of cardiac sympathetic nerve stimulation on coronary inflow were studied in previously operated conscious dogs, using electromagnetic flowmeters. Stimulation caused an increase of coronary inflow which was due mainly to an augmentation of flow during diastole. In systole, inflow changes were smaller and variable according to the strength of stimulation. The data presented indicate that an arteriolar dilatation may play a role in augmenting coronary inflow. In several instances, the increase of coronary inflow was preceded by a phase of reduction which suggested the possibility of coronary vasoconstriction as a primary direct effect of cardiac sympathetic activation.