The adrenergic nervous system is chronically activated in patients with congestive heart failure (CHF). One consequence of this is depletion of the normally high levels of myocardial norepinephrine. In this study, myocardial norepinephrine and dopamine concentrations from the left ventricular walls of 3 patients undergoing cardiac transplantation for severe refractory CHF are reported. The dopamine/norepinephrine ratios were high in all 3 patients (29, 58 and 26%). This finding supports data from animal studies suggesting a change in the rate-limiting step for myocardial norepinephrine synthesis in CHF. Conversion of tyrosine to dopa by tyrosine hydroxylase is replaced as the rate-limiting step by inability to hydroxylate dopamine to norepinephrine. Thus, dopamine accumulates while norepinephrine is depleted.
Bibliographical noteFunding Information:
From the Minneapolis Veterans Administration Medical Center, and the University of Minnesota Division of Cardiology and Cardiovascular Surgery, Minneapolis, Minnesota. This research was supported by the Medical Research Service of the Veterans Administration and by Grant 5ROl-HL22977. National Heart, Lung, and Blood Institute, Bethesda, Maryland. Manuscript received May 12, 1983; revised manuscript received July 27, 1983, accepted August 1, 1983.