Lithium-sodium countertransport in erythrocytes of normal and hypertensive subjects. Relationship with age and plasma renin activity.

Abstract

SUMMARY Li,-Na a countertransport was measured in red blood cells of 58 normotensive subjects (27 females and 31 males), 60 patients with essential hypertension (26 females and 34 males), and in 28 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,-Na o 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 | -Na o 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 • hypertension A N altered cation transport in red blood cells of essential hypertensive subjects has often been observed and has been sometimes referred to as a useful test differentiating essential from secondary hypertension.1 " 4 The abnormality concerning different mechanisms of sodium transport, has been also detected in normotensive people born to parents with essential hypertension:5 ' 6 it could have a predictive value for a later hypertensive disease. One of the cation transport mechanisms that has been found abnormal in the erythrocytes of patients with essential hypertension is the Li r Na o countertransport, 2 6 albeit a consistent overlap of the values of the countertransport between the normotensive and hypertensive groups has been further reported by several authors. -7 8The aim of the present study was to correlate the Li r Na 0 countertransport in the red blood cells of normotensive and hypertensive people with other clinical and biochemical parameters usually investigated in these subjects and particularly with the plasma renin activityF Methods Selected for study were 58 (27 females and 31 males) normotensives, 60 patients (26 females and 34 males) with essential hypertension, and 28 patients (19 females and 9 males) with secondary hypertension. The mean age of the three groups of patients was 38 ± 15, 46 ± 11, and 41 ± 16 years respectively. Among secondary hypertensives, 13 had hypertension secondary to kidney disease, eight had hyperaldosteronism (6 hyperplasia and 2 adenoma), four had polycystic kidney disease, and three had renovascular hypertension. All patients were untreated for at le...

Sodium-lithium countertransport and hypertension in Rochester, Minnesota.

“…Correlations of sodium-lithium countertransport with age, 17 measures of body size, 18 and plasma lipid levels 5 have been reported in previous studies. However, because samples for these studies were small or were ascertained through referral clinics or hospitals, the role of these concomitant traits in predicting sodium-lithium countertransport in the general population has remained uncertain.…”

Assay of human erythrocyte sodium‐dependent lithium efflux: the importance of timing of blood sampling

“…3). Our finding is at variance with that reported by Winocour et al [14], who showed a correlation, albeit a weak one, between aldosterone and SLC, but is in consonance with that found by Brugnara et al [4].…”

“…Unfortunately, however, subsequent reports have shown a considerable overlap in SLC values between normotensive control subjects and hypertensive patients [4][5][6]. The cause(s) of the implied insufficient specificity of SLC is not clear, but it may be that abnormality of the transport system is present only in a subset of patients with essential hypertension [7].…”

Red-cell sodium-lithium countertransport and fractional excretion of lithium in normal and hypertensive humans.

“…Further, Brugnara et al 39 studied normotensive subjects between 10 and 80 years of age, and countertransport correlated inversely with age in their subjects. Burke et al 40 studied 120 normotensive subjects across a similar age range, and they also found a decrease in countertransport with age.…”