ANGIOTENSIN-CONVERTING ENZYME-INHIBITION CORRECTS NA+ H+ EXCHANGER OVERACTIVITY IN ESSENTIAL-HYPERTENSION/

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 expressio n in lymphocytes from patients with essential hypertension. Thirty-thr ee hypertensive patients and 27 normotensive subjects were studied. Ma ximal sodium-proton exchange activity was determined by acidifying cel l 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 (beta-act in). With the 100% confidence (upper) limit of the normotensive popula tion as a cutoff point, a subgroup of 11 hypertensive patients had an abnormally high lymphocyte Na+/H+ exchange activity (group A). The act ivity of the exchanger was within the normal range in the remaining pa tients (group B). After 6 months of quinapril treatment the activity o f the exchanger decreased to normal values (P < .001) in patients from group A, but remained unchanged in patients from group B. The NHE-1 m RNA expression was not modified with treatment neither in patients fro m the group A, nor in patients from the group B. These results suggest that chronic angiotensin enzyme inhibition with quinapril abolishes N a+/H+ exchange overactivity present in lymphocytes from a subgroup of hypertensive patients. This effect appears to be independent of change s in the expression of the mRNA encoding for the NHE-1 isoform of the exchanger. (C) 1997 American Journal of Hypertension, Ltd.