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Derivation of urinary dopamine from plasma dopa
R Zimlichman1, P D Levinson, G Kelly
1Hypertension Unit, Soroka Medical Center, Ben-Gurion University, Beer-Sheva, Israel.
Clinical Science (London, England : 1979)
|November 1, 1988
Summary
Plasma dopa (3,4-dihydroxyphenylalanine) is the primary source of urinary dopamine (DA; 3,4-dihydroxyphenethylamine). This study quantifies the kidney
Area of Science:
- Nephrology
- Endocrinology
- Biochemistry
Background:
- Urinary dopamine (DA) is a metabolite with potential physiological roles.
- The primary source of urinary DA has not been definitively established.
Purpose of the Study:
- To determine the extent to which circulating dopa (3,4-dihydroxyphenylalanine) contributes to urinary dopamine excretion.
Main Methods:
- Infusion of tritiated dopa ([3H]dopa) into the renal artery of anesthetized foxhounds.
- Measurement of labeled and unlabeled dopa and DA in plasma and urine.
- Calculation of renal plasma flow using p-aminohippurate clearance.
Main Results:
- A small percentage of infused [3H]dopa was excreted as [3H]DA (0.59-0.68%).
- Arterial dopa concentrations and renal plasma flow supported the endogenous urinary DA excretion through dopa uptake and decarboxylation.
- Plasma dopa accounts for all endogenous urinary DA excretion.
Conclusions:
- Circulating plasma dopa is the principal precursor for urinary dopamine.
- Kidney's uptake and decarboxylation of plasma dopa explain urinary DA levels.