The Direct Effects of Norepinephrine, Epinephrine, and Methoxamine on Myocardial Contractile Force in Man

The effects of 5 sympathomimetic amines on myocardial contractile force were determined with the Walton-Brodie strain-gage arch in 16 patients undergoing operations for congenital heart disease. Equal doses of norepinephrine and epinephrine produced almost identical increments in myocardial contractile force; equipressor doses of methoxamine resulted in little or no change in the force of contraction. Mephentermine and metaraminol produced increments in myocardial contractile force similar to those following norepinephrine administration but the duration of action was longer. The results of these studies indicate that there are no qualitative differences in the actions of these amines on cardiac contractile force of dog and man and provide a basis for the rational clinical use of these agents.