Hypertension Clinical Studies Lithium-Sodium Countertransport in Erythrocytes of Normal and Hypertensive Subjects Relationship with Age and Plasma Renin Activity

with secondary hypertension (19 females and 9 males). The mean values ( ± SEM) expressed as mmol Li (1 red cells x hr)"1 were 0.18 ± 0.02 (females) and 0.20 ± 0.01 (males) in the control group, 0.34 ± 0.04 (females) and 0.39 ± 0.03 (males) in essential hypertension, 0.16 ± 0.03 (females) and 0.19 ± 0.02 (males) in secondary hypertension. The mean value of Li,-Nao countertransport obtained in essential hypertension was statistically different from those obtained in both normals (p < 0.001) and patients with secondary hypertension (p < 0.001). A negative correlation was found between age and Li|-Nao countertransport in normotensive males (r = — 0.648; p < 0.001) but neither in normal females nor in patients with essential hypertension. A positive correlation (r = + 0.425; p < 0.05) was found between plasma renin activity after intravenous furosemide and Ll-Na countertransport in essential hypertension. These findings support the hypothesis of a characteristic cation transport across the red blood cell membrane of patient with essential hypertension which might be correlated with the plasma renin activity. (Hypertension 5:529-534, 1983) KEY WORDS • • erythrocyte countertransport • age • plasma renin activity • hypertensio