Intraerythrocyte sodium concentration in black families with and without hypertension.

Blood pressure and intraerythrocyte sodium and potassium concentration were investigated in 59 male inhabitants of an urban quarter of Kinshasa, aged 10 years and older. Two subjects were excluded because they were on antihypertensive treatment. Seventeen subjects were normotensive with both parents normotensive (group 1); 9 subjects were normotensive with at least one hypertensive parent (group 2); 5 subjects were untreated hypertensives (group 3) and 26 subjects could not be classified (group 4). Systolic pressure and intraerythrocyte sodium concentration (expressed in mmol/1 cells) were significantly higher in normotensive subjects with a positive family history of hypertension (group 2) than in normotensive males of comparable age, weight and height, born to normotensive parents (group 1). Untreated hypertensives (group 3) were older and their intraerythrocyte sodium concentration was higher in comparison to normotensives without positive family history of hypertension. The intraerythrocyte potassium concentration did not differ significantly among groups 1, 2 and 3. When the first three groups of participants, or all the subjects with the exclusion of treated hypertensives, were considered, no relationship could be demonstrated between the level of blood pressure and the intraerythrocyte sodium and potassium concentration. It can be concluded that parental hypertension in normotensive African blacks is associated with increased intraerythrocyte sodium concentration.