Racial differences in hypertension-associated red cell sodium permeability

Abstract

The prevalence and severity of essential hypertension varies greatly among human populations. Some of this variation is undoubtedly due to differences in dietary Na⁺ levels¹. However, even within groups which consume large amounts of salt, not all members develop increased blood pressure. Furthermore, the clinical expression of hypertension varies among races, and American blacks have particularly severe symptoms. These observations, in addition to a familial pattern in the occurrence of essential hypertension, suggest important genetic influences. Recent studies, primarily of northern European populations, have demonstrated abnormal erythrocyte Na⁺ transport in affected individuals^2–5 and in approximately half the members of kindreds founded by a hypertensive progenitor^4,5. We have found that red cell Na⁺ transport can be assessed simply by measuring the unidirectional passive influx of ²²Na⁺ into ouabain-treated erythrocytes⁵ and have applied this technique to American blacks with essential hypertension. The results suggest a complete absence of the abnormal erythrocyte Na⁺ transport which is characteristic of white patients with essential hypertension. Thus, among American blacks, essential hypertension may have either a different genetic basis or a substantially different expression.