Endothelial glycoconjugates: a comparative lectin study of the brain, retina and myocardium.
There is evidence that the endothelial cell (EC) glycocalyx is a significant determinant of vascular permeability, acting as a charge-size filter to permeant molecules. We have therefore examined its oligosaccharide composition in 3 classes of microvessel with differing permeabilities. EC in rat brain, retina and myocardium were labelled with a panel of lectins and subjected to a semiquantitative analysis. Surprisingly, no substantial differences were evident for any lectin labelling between the 3 microvessel types despite their marked morphophysiological diversity. In particular, all showed substantial sialic acid expression, with Maackia amurensis (MAA) labelling sialic acid in an alpha2-3 linkage to beta-galactose and Sambucus nigra (SNA) recognising sialic acid in an alpha2-6 linkage to beta-galactose. Arachis hypogaea (PNA) binding after neuraminidase digestion indicated the presence of Gal beta1-3GalNAc attached to terminal sialic acid. The results therefore show that the sequences NeuNAc alpha2-3Gal beta1-3GalNAc and NeuNAc alpha2-6Gal beta1-3GalNAc are strongly expressed in the 3 microvessel types irrespective of their permeability properties. This homogeneity suggests that these lectin ligands may be involved in a common set of EC functions, e.g. cell:cell and cell:matrix interactions. However, we cannot rule out the possibility that glycocalyx differences may exist between vessels in the paracellular cleft which may alter its filtration properties.
Lawrenson
J G
JG
Reta Lila Weston Institiute of Neurological Studies, University College London, UK. J.G.Lawrenson@city.ac.uk
Cassella
J P
JP
Hayes
A J
AJ
Firth
J A
JA
Allt
G
G
D000818:Animals; D001921:Brain / Q000033:anatomy & histology*; D002560:Cerebrovascular Circulation; D004730:Endothelium, Vascular / Q000033:anatomy & histology; D006321:Heart / Q000033:anatomy & histology*; D037102:Lectins / Q000378:metabolism; D008297:Male; D008833:Microcirculation; D051381:Rats; D017208:Rats, Wistar; D012160:Retina / Q000033:anatomy & histology*
D037102:Lectins