Angiotensin Converting Enzyme Inhibition Corrects Na+/H+ Exchanger Overactivity in Essential Hypertension

Abstract In this study, we investigated whether antihypertensive treatment with the angiotensin converting enzyme inhibitor quinapril modifies Na + /H + exchanger activity or NHE-1 (isoform of the exchanger) mRNA expression in lymphocytes from patients with essential hypertension. Thirty-three hypertensive patients and 27 normotensive subjects were studied. Maximal sodium-proton exchange activity 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 transcript level of NHE-1 was measured by reverse transcription-polymerase chain reaction in comparison with a constitutively expressed reference gene ( β -actin). With the 100% confidence (upper) limit of the normotensive population as a cutoff point, a subgroup of 11 hypertensive patients had an abnormally high lymphocyte Na + /H + exchange activity (group A). The activity of the exchanger was within the normal range in the remaining patients (group B). After 6 months of quinapril treatment the activity of the exchanger decreased to normal values ( P + /H + exchange overactivity present in lymphocytes from a subgroup of hypertensive patients. This effect appears to be independent of changes in the expression of the mRNA encoding for the NHE-1 isoform of the exchanger.