Renal dopamine excretion in healthy volunteers after oral ingestion of l-Dopa |
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Authors: | M Barthelmebs P Mbou D Stephan M Grima and JL Imbs |
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Institution: | Institut de Pharmacologie, URA DO589 CNRS, Facultéde Médecine, 11 rue Humann;Service d'Hypertension et Maladies Vasculaires, CHRU, 1 place de l'Hôpital, 67000 Strasbourg, France |
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Abstract: | Summary— l -Dopa is converted to dopamine by aromatic- l -amino acid decarboxylase (AADC). In the kidney, proximal tubular epithelial cells are rich in AADC and urinary free dopamine excretion is a marker for endorenal extraneuronal dopamine synthesis. The urinary free dopamine excretion was analysed in a double-blind cross-over study after oral ingestion of l -Dopa or a placebo in five healthy volunteers. The drug ingestions were separated by one week's wash-out. Since in a preliminary study, two volunteers ingesting a single l -Dopa dose of 500 mg with breakfast experienced nausea, the five volunteers of the present study were given 300 mg l -Dopa (50 mg at 9 am with breakfast, 100 mg before lunch and 150 mg before dinner) without any adverse effects. l -Dopa induced an increase in 24-h urinary dopamine excretion (HPLC with electrochemical detection). Free urinary dopamine (1900 μg/24 h) accounted for 0.8% of the daily oral l -Dopa dose and represented 10% of total urinary dopamine excretion. l -Dopa treatment had no significant effect on mean ambulatory arterial blood pressure and heart rate measured from 9 am to 6 pm (Spacelabs) or on 24 h urinary water and sodium excretion. |
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Keywords: | l-Dopa DA synthesis renal DA excretion |
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