RESUMO
A cellular calcium-magnesium antagonism seems to be involved in the pathogenesis of primary hypertension. Total plasma, intracellular, and membranous calcium (Ca) and magnesium (Mg) contents were determined in 39 untreated patients with essential hypertension (EH) and 40 normotensive healthy subjects (NT). Membranous and intracellular measurements were performed in erythrocytes. Ca and Mg contents were measured by atomic absorption spectroscopy and membrane protein was determined according to Bradford's method as a membranous reference. There was no significant difference in plasma Ca (NT: 2.60 +/- 0.15 v EH: 2.64 +/- 0.17 mmol/L) and Mg concentrations (NT: 0.83 +/- 0.12 v EH: 0.87 +/- 0.14 mmol/L) in the studied groups. Intracellular Mg (NT: 1.72 +/- 0.15 mmol/L v EH: 1.64 +/- 0.19 mmol/L) and Ca (NT: 2.06 +/- 0.20 mmol/L v EH: 2.10 +/- 0.24 mmol/L) contents were also not significantly different between groups. Membrane Ca content was significantly increased in the EH group (2.23 +/- 0.32 micromol/g membranous protein) compared to controls (1.05 +/- 0.30 micromol/g membranous protein, P < .01). On the contrary, membranous Mg content was significantly decreased compared to controls (0.31 +/- 0.09 v 0.50 +/- 0.10 mmol/g membranous protein content, P < .01). The Ca/Mg ratio in membranes was significantly increased in EH as compared to healthy subjects (P < .01) and correlated to mean arterial blood pressure values (r = 0.47, P < .01). We conclude that the membranous alterations of Ca and Mg metabolism, shown by increased Ca/Mg ratio in red cell membranes of hypertensive subjects, may play a role in the pathogenesis of primary hypertension.