Biosynthesis of Norepinephrine in Isolated Canine Heart

Abstract

Radioactive dopamine was injected into the blood that was perfusing an isolated heart preparation. Analysis of the norepinephrine obtained from the heart 1 hour later demonstrated that it contained radioactivity. Between 1.4 and 10.8 percent of the norepinephrine present had been formed from the dopamine. The turnover of norepinephrine was substantially higher in the ventricles than in the atria.

Sympathomimetic Actions of Reserpine Administered During Treatment with Dopamine in the Dog

“…However, as dopamine inhibits noradrenaline re-uptake, blocks monoamine oxidase by being a preferential substrate and acts as a precursor for noradrenaline synthesis (9,10,11), the possibility that another indirect mechanism may be involved in the reserpine reversal induced by dopamine cannot be dismissed. In our present studies on dogs, reserpine reversal occurred after cocaine though its potency was weaker than that in dopamine infused animals.…”

Natriuretic Peptides: Physiologic and Analytic Considerations

“…After discovering that norepinephrine is synthesized in the heart in 1963, 1 Braunwald and colleagues 2 published a paper the following year in the American Journal of Medicine entitled: ''The heart as an endocrine organ.'' Although not scientifically documented before this seminal finding, the theory that the heart might possess endocrine functions emerged even earlier.…”

Reduction of Cardiac Tyrosine Hydroxylase Activity in Experimental Congestive Heart Failure

“…Moreover, it has been shown that in experimental heart failure there is a reduction in the response of the heart to sympathetic nerve stimulation, and it has been postulated that the heart failure state may be intensified by loss of intrinsic neurotransmitter stores (5). Cardiac stores of norepinephrine are primarily synthesized from tyrosine in the heart (6,7), although up to 20% may be derived from the uptake of exogenous norepinephrine (8). The objective of this study was to investigate cardiac synthesis of norepinephFrom the Cardiology Branch and Laboratory of Clinical Biochemistry, National Heart Institute, Bethesda, Maryland.…”