1. The role of the adrenergic nervous system in the regulation of plasma renin activity was investigated in fourteen healthy volunteers. Special attention was devoted to 3,4-dihydroxyphenethylamine (dopamine) because this amine is not only a precursor of noradrenaline, but also a catecholamine with its own functions. The adrenergic nervous system was activated by a change of posture because this offers a simple and reproducible stimulus; its effects were studied during a normal diet and also after restriction of sodium.
2. With both diets, the expected increase in plasma renin activity was observed after changing from recumbency to an upright posture. This was associated with a decrease in the urinary excretion of dopamine and an increase in the urinary excretion of noradrenaline and adrenaline. In addition, a positive and significant correlation was found between the urinary excretion of dopamine and sodium.
3. Our data suggest that dopamine and noradrenaline may play a complementary role in the regulation of renin secretion, but they do not necessarily act in the same direction or through similar mechanisms. Dopamine is known to be a pharmacological natriuretic agent. It may have a similar role in the physiological regulation of urinary sodium excretion.