Red cell membrane sodium transport: possible genetic role and use in identifying patients at risk of essential hypertension.

To investigate the influence of a family history of essential hypertension on abnormalities of red cell membrane sodium transport, 28 hypertensive children and their families were studied. In 15 families one or both parents had either essential hypertension or a strong family history. In 13 families neither parent had essential hypertension or a positive family history. There were significant differences between the children with a positive family history of essential hypertension compared with those without. Values are expressed as mean (SD): intracellular sodium concentration (mmol/l cells) 8.19 (2.18) compared with 6.41 (0.98); sodium efflux rate constant 0.4873 (0.1379) compared with 0.5831 (0.1104); and numbers of sodium-potassium ATPase pump sites (BMax) (nmol/l cells) 7.96 (1.71) compared with 9.56 (1.7). Significant differences were also found when the index hypertensive children were excluded and the normotensive siblings with and without hypertensive family histories were compared. These data suggest that abnormal red cell membrane sodium transport has a familial component, and although it is not caused by the hypertension it may be the earliest pathophysiological step in its development, perhaps allowing the identification of children at risk of essential hypertension.