Studies of the interrelationship between plasma norepinephrine, plasma renin activity and acute myocardial infarction in dogs.

Serial determinations of plasma norepinephrine and renin activity were made in dogs following acute ligation of the left anterior descending coronary artery. Increases in both substances closely paralleled increases in creatine phosphokinase activity, heart rate and the incidence of ventricular premature contractions. Following acute myocardial infarction, significant correlations were found to exist between plasma norepinephrine and plasma renin activity and between the levels of these vasoactive substances and the measured indices of ischemic damage. These data suggest that changes in vasoactive systems associated with myocardial infarction may contribute to the extent of ischemic injury.