A Paradoxical Fall in Urine Dopamine Output When Patients with Essential Hypertension Are Given Added Dietary Salt

Abstract

The effect of dietary Na on the urine dopamine excretion of 8 hypertensive patients and 6 matched controls was studied under metabolic balance conditions over a 2 wk period during which dietary Na intake was increased from 20-220 mmol/day. The control group showed the expected increase in dopamine excretion in response to Na but the hypertensive patients showed an initial fall followed by a return to baseline values. Neither group showed a rise in blood pressure but the hypertensive patients showed a greater weight gain on salt loading, although this change was not significant. The cumulative Na balance was greater and more prolonged in the hypertensive patients, although this difference also did not attain statistical significance. This defect in dopamine mobilization may be important in relation to renal Na handling by patients with essential hypertension.