SUPPRESSION OF ENDOTHELIN-1 PRODUCTION IN CULTURED HUMAN UMBILICAL VEIN ENDOTHELIAL-CELLS BY HEPARIN FRACTIONS SEPARATED BY STRONG ANION-EXCHANGE CHROMATOGRAPHY

Heparin has been shown to lower the production/secretion of the vasoco nstrictive peptide endothelin-1, Endothelin-1 production is stimulated by thrombin, and it has been proposed that heparin binds to the anion -binding exosite of thrombin, preventing it from stimulating endotheli n-1 production, To further test this proposal, heparin was fractionate d by strong anion exchange chromatography (QAE-Sephadex A-25) into fou r fractions, These fractions had anticoagulant activities that increas ed linearly with charge, as defined by the median salt concentration n eeded for elution from the column, The fractions also differed in the total number of sulfates per mole of heparin, which was dependent on t he molecular mass of the fractions rather than charge density, The fra ctions were found to significantly differ from each other in their abi lity to suppress endothelin-1 production, The fraction eluting from th e ion exchange column at the highest salt concentration had the greate st suppressive effect, Addition of sodium or potassium chloride to the media interfered with the ET-1 suppressive effect of unfractionated h eparin, whereas lithium chloride had no effect, These data show that c harge interactions between heparin and thrombin may be important in re gulating the production of endothelin-1 and in regulating other thromb in-dependent functions. (C) 1996 Academic Press, Inc.