[Administration of the catecholamine precursor, L-DOPA, for evaluating their in vivo biosynthesis in hypertension]

The activity of the sympathetico-adrenal system was studied in 19 healthy individuals and in 40 patients with grade IB and IIA hypertensive disease. The excretion of free and conjugated forms of catetcholamines (adrenalin, noradrenalin and dopamine) and the precursor of their synthesis DOPA was determined. Comparison of these values in the control period and after per os administration of L-DOPA (levodopa) showed that administration of the precursor makes it possible to appraise catecholamine biosynthesis in vivo on the level of the intact organism. The results indicate that in patients with hypertensive disease of the early stages the production of dopamine is increased, whereas that of noradrenaline is reduced.