title: Sodium selective erythrocyte glycocalyx and salt sensitivity in man.
abstract: Negatively charged surfaces of erythrocytes (RBC) reflect properties of the endothelial glycocalyx. Plasma electrolytes counteract these charges and thus control the repulsive forces between RBC and endothelium. Although Na(+) is supposed to exert a rather high affinity to the RBC surface, a direct comparison between Na(+) and K(+) in counteracting the RBC surface has been never made. Therefore, we measured Na(+)/K(+) selectivity of the RBC surface in 20 healthy volunteers applying the previously published salt blood test (SBT). It turned out that the Na(+)/K(+) selectivity ratio of the RBC glycocalyx is on average 6.1 ± 0.39 (ranging from 3 to 9 in different individuals). Considering standard plasma Na(+) and K(+) concentrations, binding probability of Na(+)/K(+) at the RBC surface is about 180:1. The SBT reveals that plasma K(+) counteracts only about 7% of the negative charges in the RBC glycocalyx. As an in vivo proof of principle, a volunteer's blood was continuously tested over 6 months while applying a glycocalyx protective polyphenol-rich natural compound (hawthorn extract). It turned out that RBC Na(+) sensitivity (the inverse of Na(+) buffer capacity) decreased significantly by about 25% while Na(+)/K(+) selectivity of the RBC glycocalyx declined only slightly by about 8 %. Taken together, (i) plasma Na(+) selectively buffers the negative charges of the RBC glycocalyx, (ii) the contribution of K(+) in counteracting these negative surface charges is small, and (iii) natural polyphenols applied in vivo increase RBC surface negativity. In conclusion, low plasma Na(+) is supposed to favor frictionless RBC-slipping through blood vessels.
authors.affiliation: Institute of Physiology II, University of Münster, Robert-Koch-Str. 27b, 48149, Münster, Germany, oberlei@uni-muenster.de.
authors.forename: Hans
authors.initials: H
authors.lastname: Oberleithner
mesh_terms: D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002478:Cells, Cultured; D027825:Crataegus / Q000737:chemistry; D004912:Erythrocytes / Q000187:drug effects / Q000378:metabolism*; D019276:Glycocalyx / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D010936:Plant Extracts / Q000494:pharmacology; D059808:Polyphenols / Q000494:pharmacology; D011188:Potassium / Q000097:blood* / Q000494:pharmacology; D012964:Sodium / Q000097:blood* / Q000494:pharmacology; D055672:Static Electricity; D055815:Young Adult
chemical_list: D010936:Plant Extracts; D059808:Polyphenols; D012964:Sodium; D011188:Potassium