Related Experiment Videos
Elevated left ventricular myocardial dopamine in preterminal idiopathic dilated cardiomyopathy
Insights
Congestive heart failure (CHF) causes chronic adrenergic nervous system activation, depleting myocardial norepinephrine. This study found high dopamine/norepinephrine ratios in CHF patients, indicating altered norepinephrine synthesis.
Area of Science:
- Cardiology
- Neuroscience
- Biochemistry
Background:
- The adrenergic nervous system is chronically activated in patients with congestive heart failure (CHF).
- This activation leads to depletion of myocardial norepinephrine, a critical neurotransmitter in the heart.
- Understanding these changes is vital for managing CHF progression.
Purpose of the Study:
- To investigate myocardial norepinephrine and dopamine concentrations in patients with severe refractory congestive heart failure.
- To explore the implications of these concentrations on norepinephrine synthesis pathways in CHF.
Main Methods:
- Analysis of myocardial tissue from the left ventricular walls of 3 patients undergoing cardiac transplantation for severe refractory CHF.
- Quantification of norepinephrine and dopamine concentrations within the myocardial tissue.
Main Results:
- High dopamine/norepinephrine ratios were observed in all 3 patients (29%, 58%, and 26%).
- These findings suggest a shift in the rate-limiting step of myocardial norepinephrine synthesis in CHF patients.
- Evidence points to impaired dopamine to norepinephrine hydroxylation as a key factor.
Conclusions:
- The study supports animal data suggesting altered norepinephrine synthesis in CHF.
- Accumulation of dopamine and depletion of norepinephrine are characteristic biochemical changes in the failing heart.
- These biochemical alterations highlight potential therapeutic targets for CHF.
Abstract:
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.