Sources and Physiological Significance of Plasma Dopamine Sulfate

• Published in: The journal of clinical endocrinology and metabolism Vol. 84; no. 7; pp. 2523 - 2531
• Main Authors: Goldstein, David S, Swoboda, Kathryn J, Miles, John M, Coppack, Simon W, Aneman, Anders, Holmes, Courtney, Lamensdorf, Isaac, Eisenhofer, Graeme
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Endocrine Society 01-07-1999
• Subjects: Adult; Aminoacids, peptides. Hormones. Neuropeptides; Analytical, structural and metabolic biochemistry; Aromatic-L-Amino-Acid Decarboxylases - deficiency; Arteries; Autonomic Nervous System Diseases - blood; Biological and medical sciences; Blotting, Western; Dopamine - analogs & derivatives; Dopamine - blood; Dopamine Agents; Fasting; Female; Food; Fundamental and applied biological sciences. Psychology; Gastrointestinal Neoplasms - blood; Gastrointestinal Neoplasms - surgery; Humans; Levodopa - administration & dosage; Levodopa - blood; Male; Nitroprusside - administration & dosage; Portal Vein; Proteins; Trimethaphan - administration & dosage; United States; North America; America; Human; Dopamine; Distribution; Biosynthesis; Physiology; Sulfates; Biological activity; Feeding; Blood plasma
• ISSN: 0021-972X; 1945-7197
• DOI: 10.1210/jcem.84.7.5864

Dopamine in the circulation occurs mainly as dopamine sulfate, the
sources and physiological significance of which have been obscure. In
this study, plasma concentrations of dopamine sulfate were measured
after a meal, after fasting for 4 days, and during iv L-DOPA,
nitroprusside, or trimethaphan infusion in volunteers; after dopamine
infusion in patients with l-aromatic-amino-acid
decarboxylase deficiency; in arterial and portal venous plasma of
gastrointestinal surgery patients; and in patients with sympathetic
neurocirculatory failure. Meal ingestion increased plasma dopamine
sulfate by more than 50-fold; however, prolonged fasting decreased
plasma dopamine sulfate only slightly. L-DOPA infusion produced much
larger increments in dopamine sulfate than in dopamine; the other drugs
were without effect. Patients with l-aromatic amino acid
decarboxylase deficiency had decreased dopamine sulfate levels, and
patients with sympathetic neurocirculatory failure had normal levels.
Decarboxylase-deficient patients undergoing dopamine infusion had a
dopamine sulfate/dopamine ratio about 25 times less than that at
baseline in volunteers. Surgery patients had large arterial-portal
venous increments in plasma concentrations of dopamine sulfate, so that
mesenteric dopamine sulfate production accounted for most of urinary
dopamine sulfate excretion, a finding consistent with the localization
of the dopamine sulfoconjugating enzyme to gastrointestinal tissues.
The results indicate that plasma dopamine sulfate derives mainly from
sulfoconjugation of dopamine synthesized from L-DOPA in the
gastrointestinal tract. Both dietary and endogenous determinants affect
plasma dopamine sulfate. The findings suggest an enzymatic gut-blood
barrier for detoxifying exogenous dopamine and delimiting
autocrine/paracrine effects of endogenous dopamine generated in a“
third catecholamine system.”