We examined the relationship between the excretion of electrolytes (sodium, potassium and calcium), dopamine and digoxin-like immunoreactive substance in 41 young healthy female subjects (age 18-23 years) in order to study the interaction of electrolyte intake on dopamine and digoxin-like immunoreactive substance--factors which have been postulated to have a pathogenic role in hypertension. Sodium excretion was significantly correlated with dopamine excretion (r = 0.545, P < 0.0005) and digoxin-like immunoreactive substance (r = 0.359, P < 0.02). There was also a significant correlation between calcium and digoxin-like immunoreactive substance (r = 0.345, P < 0.03). Stepwise multiple regression analysis further confirmed that sodium is the only contributor to dopamine excretion and calcium is the only contributor to digoxin-like immunoreactive substance (r2 = 0.114). We conclude that in young healthy subjects dopamine excretion is determined partly by sodium intake and that the excretion of digoxin-like immunoreactive substance is independent of sodium intake.