Dichlormagnesium-aspartate-hydrochloride was given to 12 patients with mild hypertension in antihypertensive indication at a dose of 10.5 mmol Mg2+/day for 3 months. Blood pressure normalized (from 161.7 +/- 3.4/95.8 +/- 0.8 mmHg to 140.4 +/- 4.0/81.7 +/- 0.9 mmHg, after the third month (p < 0.01). While no changes in Mg2+ concentration in serum were observed in patients with normomagnesaemia, in hypomagnesaemic patients vS-Mg level normalized. Renal excretion of Mg2+ increased: from 3.41 +/- 0.36 before to 5.7 +/- 0.57 mmol Mg2+/24 h after treatment, p < 0.01. Mean plasma serotonin (5HT) concentration showed no changes, although a trend towards an increase in platelet 5HT content was observed. Elevated pre-treatment plasma 5-hydroxyindole acetic acid (5HIAA) concentrations normalized (from 137.29 +/- 20.3 to 78.96 +/- 31.64 nmol/l after the third month, p < 0.05). These findings point to a platelet-stabilizing effect of Mg2+. Fractional excretion of 5HIAA increased (from 1.42 +/- 0.27 to 5.4 +/- 1.22 after treatment, p < 0.01) while mean urinary 5HIAA excretion remained unchanged. It is deduced that a) total body 5HT and 5HIAA production was not affected; b) a long-term supplementation of Mg2+ stimulates the transport of 5HIAA in proximal tubules and, probably, intrarenal 5HIAA synthesis. A functional block in 5HT metabolism under Mg2+ treatment is anticipated. Thus, Mg2+ supplementation has renal and extrarenal effects that are important in treating hypertension and its complications.

Institute of Preventive and Clinical Medicine Centre of Clinical Pharmacology Bratislava Slovak Republic