SODIUM-TRANSPORT ACTIVITY IN CHEEK EPITHELIAL-CELLS FROM ADOLESCENTS AT INCREASED RISK OF HYPERTENSION

Sodium transport including amiloride-sensitive Na+/H+ antiporter activ ity was measured in cheek epithelial cells of adolescents displaying e ither high or low BP tracking characteristics and in a subgroup of hig h BP tracking adolescents exhibiting a positive family history of hype rtension. From the BP tracking behaviour of over 500 adolescents measu red over a period of three years, 24 low BP tracking and 29 high BP tr acking adolescents were recruited for the study. Cheek cells were coll ected from these subjects and proton-dependent, amiloride-sensitive Na +/H+ antiporter activity and the response of this antiporter to a prot on gradient were measured. Cheek cell Na+/H+ antiporter activity was 5 0% lower (P = 0.0004) in the high BP tracking group (1.02 +/- 0.15 nmo l Na+/mg protein/5 min (mean +/- SEM) compared with the activity in th e low BP tracking group (2.05 +/- 0.24). A significantly lower Na+/Hantiporter activity (69%; P < 0.01) was also apparent in the high BP t racking adolescents with family history of hypertension (n = 7) compar ed with the low BP tracking group. The graded response of cheek cell N a+/H+ antiporter activity to the proton gradient was 58% lower (P = 0. 0039) for adolescents in the high BP tracking group compared with the low BP tracking group. Passive Na+ influx was also significantly lower in the cheek cells of the high BP tracking group. Our results therefo re show that the activity of the Na+/H+ antiporter in cheek cells and the passive Na+ transport activity are lower in those adolescents cons idered at greatest risk of future development of essential hypertensio n. These findings parallel recent observations in cheek cells from adu lt essential hypertensive subjects.