Effects of angiotensin converting enzyme inhibitor (captopril) on erythrocyte sodium ion transport systems in patients with essential hypertension

We mesured erythrocyte sodium ion transport systems in essential hypertensive and normotensive subjects. Furthermore, the effects of angiotensin converting enzyme inhibitor, captopril, on sodium ion transport systems were investigated. The passive Na+permeability of erythrocyte membrane was significantly higher and the erythrocyte Na+-K+cotransport was lower in patients with essential hypertension than in the normal subjects. However, the Na+- K+pump activity and the Na+-Li+countertransport were not significantly different between in the hypertensive subjects and in the normal subjects. After administration of captopril, the passive Na+permeability was reduced and the Na+-K+cotransport was increased in the erythrocytes of hypertensive subjects . Plasma renin activity and plasma aldosterone concentration were altered by captopril, but did not correlate with the changes in Na+transport systems. These date suggest that the abnormal Na+transport systems are associated with essential hypertension and the effects of capfopril on Na+transport systems may contribute to its antihypertesive action.