MEMBRANE SODIUM-PROTON EXCHANGE AND PRIMARY HYPERTENSION

Recent studies have revealed that an enhancement of sodium-Proton exch ange is a frequently observed ion transport abnormality in essential h ypertension. An altered antiport activity not only is measurable in bl ood cells of hypertensive subjects ex vivo but also is detectable in s keletal muscle in vivo. Several lines of argument suggest that the alt ered antiport activity is not an epiphenomenon of hypertension: 1) the increased activity is found only in a subgroup of patients with high blood pressure, 2) it is not tightly correlated to the severity or dur ation of hypertension, and 3) high sodium-proton exchange activity per sists over time and is not affected by antihypertensive treatment. Ava ilable evidence suggests that enhanced sodium-proton exchange is assoc iated with or a cause for the structural alterations found in resistan ce vessels of hypertensive individuals (media hypertrophy) and left ve ntricular hypertrophy. This review summarizes some of the physiologica l properties and roles of the sodium-proton exchanger and discusses it s kinetic properties in essential hypertension. Furthermore, the reaso ns for the enhanced antiport activity and its potential implications r egarding the pathogenesis of hypertension are discussed.