Comparison of Left and Right Sympathetic Stimulations on the Phasic Coronary Flow

In thirteen anesthetized open chest dogs the left sympathetic stimulation decreased the systolic flow by augmented myocardial contractility and by sympathetic coronary vasoconstriction, while the diastolic flow was increased with the elevation of blood pressure. Both systolic and diastolic flows were increased after the stimulation suggesting metabolic vasodilatation. Coronary vasoconstriction and vasodilatation revealed parallel changes in systolic and diastolic flows. The right sympathetic stimulation induced marked tachycardia and decreased systolic and diastolic flows at the initial phase. Both systolic and diastolic flows were increased during the right sympathetic stimulation, indicating less positive inotropic effcet and less remarkable coronary vasoconstriction as well as the marked metabolic response to tachycardia.