The Li sup sup Na sup nbsp sup exchange in hypertension

Abstract

The red cell membrane Li+/Na+exchange is a heteroexchange that operates in either direction across the cell membrane. It binds either Li+ or Na+ on one side of the membrane and it exchanges the transported species for either Li+ or Na+ on the opposite side in a stoichiometric ratio of 1:1. In the population, Li+/Na+exchange is unimodally distributed but skewed to the right. Such distribution results from superimposition of two normal distributions. Many laboratories have shown that red-cell Li+/Na+ exchange is increased in patients with essential hypertension, compared with normotensive controls. Among the various alterations of cell membrane cation transport reported in hypertension, the increase of red-cell Li+/Na+ exchange has been most widely investigated and confirmed. Moreover, increased Li+/Na+ exchange has been found in some clinical conditions related to hypertension, such as overweight and diabetes. Among diabetic patients, Li+/Na+ exchange is particularly high in patients with nephropathy, hypertension, and microalbuminuria, leading to the hypothesis that it can be considered a cellular marker of the risk of developing diabetic nephropathy. Furthermore, it is associated with severe and drug-resistant hypertension, insulin resistance, vascular and cardiac hypertrophy, hyperlipidemia, obesity, family history of hypertension, and of major cardiovascular accidents suggesting that high Li+/Na+ exchange could be a biochemical marker for increased cardiovascular risk. Regardless of its the pathophysiological significance, its measurement could be of clinical use as an intermediate phenotype of increased cardiovascular risk.

Red blood cell abnormalities and hypertension

“…Odashiro et al [1] showed that the deformability of circulating RBCs might be impaired in nondiabetic hypertensive patients by a nickel mesh filtration technique [1]. Regarding membrane transport systems, alterations in sodium-lithium countertransport, sodium-potassium ATPase activity, and other electrolyte exchanges through RBC membranes have been demonstrated in hypertension [2][3][4][5]. Radosinska and Vrbjar showed that RBC deformability might be closely related to the sodium-potassium ATPase activity of RBC membranes [3].…”