PERMSELECTIVITY OF ANGIOGENIC MICROVESSELS FOLLOWING ALTERATION OF THE ENDOTHELIAL FIBER-MATRIX BY OLIGOSACCHARIDES

The endothelial glycocalyx, which is composed of integral and peripher al glycoconjugates, forms a fibrous matrix that confers macromolecular sieving properties on the microvascular wall. Changes in pore size wi thin the matrix may regulate macromolecular access to the paracellular and/or vesicular transendothelial pathways. We tested the hypothesis that modifications of the endothelial glycocalyx might play a role in the ontogeny of endothelial permselectivity in proliferating microvess els of the chick chorioallantoic membrane (CAM). Accordingly, we evalu ated the effects of Dolichos biflorus agglutinin (DBA) or Arachis hypo gaea agglutinin (PNA) lectin binding, and N'N'diacetylchitobiose or hy droxyethyl starch polysaccharide (HES) incorporation on CAM endothelia l restriction of FITC-dextrans 40 or 150 at Days 4.5 and 5.0 of develo pment. Extravasation of FITC-dextrans was determined by recording thei r perivascular interstitial intensities. Following DBA, PNA, and N'N'd iacetylchitobiose administration, interstitial accumulation of the tra cers near first-order pre- and postcapillaries, and surrounding the ca pillaries, was similar to that of controls at both Days 4.5 and 5.0. A t Day 4.5, pretreatment with HES significantly decreased extravasation of FITC-dextran 40. Thus, retention of HES molecules within the glyco calyx might tighten the matrix, and reduce access of dextran 40 to tra nsendothelial pathways across the angiogenic microvessels. (C) 1997 Ac ademic Press.