Smart mechanisms allow frictionless slipping of rather rigid erythrocytes (red blood cells, RBC) through narrow blood vessels. Nature solved this problem in an elegant way coating the moving object (RBC) and the tunnel wall (endothelium) by negative charges (glycocalyx). As long as these surfaces are intact, repulsive forces create a ‘security zone' that keeps the respective surfaces separated from each other. However, damage of either one of these surfaces causes loss of negative charges, allowing an unfavorable physical interaction between the RBC and the endothelium. It has been recently shown that any alteration of the endothelial glycocalyx leaves nasty footprints on the RBC glycocalyx. In this scenario, sodium ions hold a prominent role. Plasma sodium is stored in the glycocalyx partially neutralizing the negative surface charges. A ‘good' glycocalyx has a high sodium store capacity but still maintains sufficient surface negativity at normal plasma sodium. A ‘bad' glycocalyx shows the opposite. This concept was used for the development of the so-called ‘salt blood test' (SBT) that quantitatively measures RBC sodium store capacity of the glycocalyx and thus indirectly evaluates the quality of the inner vessel wall. In an initial step, the applicability of the SBT was tested in eight different medical facilities. The study shows that an increased salt sensitivity, as measured by the SBT, is more frequently found in individuals with a hypertensive history, despite antihypertensive medication. Taken together, preservation of the endothelial glycocalyx appears to be of utmost importance for maintaining a well-balanced function of the vascular system.

1.
Luft FC: Sodium shows no mercy on the nanomechanics of endothelial cells. Hypertension 2014;64:231-232.
2.
Weinberger MH: Salt sensitivity of blood pressure in humans. Hypertension 1996;27:481-490.
3.
Meneton P, Jeunemaitre X, de Wardener HE, MacGregor GA: Links between dietary salt intake, renal salt handling, blood pressure, and cardiovascular diseases. Physiol Rev 2005;85:679-715.
4.
Titze J, Ritz E: Salt and its effect on blood pressure and target organ damage: new pieces in an old puzzle. J Nephrol 2009;22:177-189.
5.
Sanders PW: Vascular consequences of dietary salt intake. Am J Physiol Renal Physiol 2009;297:F237-F243.
6.
Kleinewietfeld M, Manzel A, Titze J, Kvakan H, Yosef N, Linker RA, Muller DN, Hafler DA: Sodium chloride drives autoimmune disease by the induction of pathogenic TH17 cells. Nature 2013;496:518-522.
7.
Titze J, Lang R, Ilies C, Schwind KH, Kirsch KA, Dietsch P, Luft FC, Hilgers KF: Osmotically inactive skin Na+ storage in rats. Am J Physiol Renal Physiol 2003;285:F1108-F1117.
8.
Oberleithner H, Riethmuller C, Schillers H, MacGregor GA, de Wardener HE, Hausberg M: Plasma sodium stiffens vascular endothelium and reduces nitric oxide release. Proc Natl Acad Sci U S A 2007;104:16281-16286.
9.
Kusche-Vihrog K, Jeggle P, Oberleithner H: The role of ENaC in vascular endothelium. Pflugers Arch 2014;466:851-859.
10.
Oberleithner H, Kusche-Vihrog K, Schillers H: Endothelial cells as vascular salt sensors. Kidney Int 2010;77:490-494.
11.
Warnock DG, Kusche-Vihrog K, Tarjus A, Sheng S, Oberleithner H, Kleyman TR, Jaisser F: Blood pressure and amiloride-sensitive sodium channels in vascular and renal cells. Nat Rev Nephrol 2014;10:146-157.
12.
Oberleithner H: Vascular endothelium leaves fingerprints on the surface of erythrocytes. Pflugers Arch 2013;465:1451-1458.
13.
Oberleithner H, Wilhelmi M: Determination of erythrocyte sodium sensitivity in man. Pflugers Arch 2013;465:1459-1466.
14.
Luft FC: Geneticism of essential hypertension. Hypertension 2004;43:1155-1159.
15.
Oberleithner H: Sodium selective erythrocyte glycocalyx and salt sensitivity in man. Pflugers Arch 2014, DOI: 10.1007/s00424-014-1577-0.
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