Erythrocyte anion exchanger activity and intracellular pH in essential hypertension

Abstract

The present study was designed to examine the activity of the sodium-independent chloride-bicarbonate anion exchanger and the sodium-proton exchanger in erythrocytes of 30 normotensive and 35 hypertensive subjects and its relation to the previously reported decrease in erythrocyte pH. Erythrocyte cytosolic pH was measured by the pH-sensitive fluorescent probe 2′-7′-bis(2-carboxyethyl)-5(6)-carboxyfluorescein. The activity of the anion exchanger was determined by acidifying cell pH and measuring the initial rate of the net sodium-independent, 4,4′-diisothiocyanatostilbene-2,2′-disulfonic acid-sensitive, bicarbonate influx driven by an outward proton gradient. The activity of the sodium-proton exchanger was determined by acidifying cell pH and measuring the initial rate of the net sodium-dependent proton efflux driven by an outward proton gradient. The activity of the anion exchanger was higher in hypertensive than control individuals (18863±1081 vs 15 629±897 mmol/L cells per hour, P <7.19). Compared with patients with normal erythrocyte pH, patients with diminished pH were characterized by a higher activity of the anion exchanger (17 836±956 vs 20 806±1200 mmol/L cells per hour, P