Relationship between red cell sodium transport, blood pressure, and family history of hypertension.
Numerous studies have demonstrated that Na+/Li+ countertransport is increased in erythrocytes from hypertensive patients. Since Na+/Li+ countertransport is conducted through the physiologically occurring Na+/Na+ exchange, we studied the latter pathway in 20 subjects with essential hypertension and 20 normotensive subjects matched for age and sex. Ten hypertensives and six normotensives had a positive family history of hypertension. Ouabain (0.1 mM) and furosemide (0.1 mM) were used to assess the active Na+ efflux and Na+-K+-Cl- pathway. There was no significant difference between hypertensive and normotensive subjects in any of the three pathways studied. Among the 16 subjects with a positive family history of hypertension, the mean value for external Na+-dependent Na+/Na+ exchange was significantly higher than in 24 subjects with no family history of hypertension (0.0457 +/- 0.0337 versus 0.0283 +/- 0.0202; P less than 0.05). This study suggests that an inherited membrane transport defect may exist for Na+/Na+ exchange in families of hypertensive subjects.