Effect of long-term antihypertensive therapy with angiotensin converting enzyme inhibitors on red cell sodium transport

Several sodium transport abnormalities have been reported in erythrocytes from essential hypertensive patients. The possible modification of these parameters under antihypertensive treatment remains controversial. We have measured the maximal rates of the Na+/K+ pump, Na+/K+/Cl− cotransport, and Na+/Li+ countertransport and the rate constant of Na+ leak in erythrocytes from 22 essential hypertensive patient responders to angiotensin converting enzyme inhibitors quinapril or captopril, and from 17 patient nonresponders to these drugs. In the former group, sodium transport measurements were performed at the baseline placebo period and after 6 months of active treatment. The maximal rate of Na+/Li+ countertransport de creased significantly after 6 months of treatment, without differences between both groups of treatment. Angiotensin converting enzyme inhibitors did not significantly modify other sodium transport parameters. The basal activity of erythrocyte sodium transport was not different between patients who responded or not to antihypertensive treatment with those drugs, excluding a predictive value of these measurements concerning the response to angiotensin converting enzyme inhibitors.