BACKGROUND: In order to extend previous observations on the heterogeneityin labeling of rat vascular endothelium by the lectins GS I and LEA [1,2], we have conducted a surveyof several organs with a lectin panel with greater variety of carbohydrate specificity.
MATERIAL AND METHODS:Submandibular gland, duodenum, distal colon, liver, kidney, heart, skeletal muscle, adrenal gland, ovary,cerebral and cerebellar cortex of a rat have been examined by light and electron microscopy using lectin-goldprobes on Lowicryl K4M embedded tissue.
RESULTS: Five lectins (LCA, con A, LEA, RCA, WGA) labeled vascularendothelial cells in the connective tissue of all the organs studied, while PNA, EEA, TPA, LABA, UEAI expressed no detectable affinity towards endothelial cells. HPA and GS I reacted with most endothelialcells, except those in the kidney glomeruli, liver sinusoids and zona fasciculata of adrenal gland. Incerebral and cerebellar cortex GS I reacted witn pericytes of large vessels, but not with endothelialcells of the capillary bed. SDS-PAGE extracts of heart, skeletal muscle and cerebral cortex reveal thatdifferences in GS I labeling depend, at least in part, on 40 and 200 kD glycoproteins, present in heartand skeletal muscle, but not cerebral cortex.
CONCLUSIONS: Data indicate, that GS I, widely used for selectivehistochemical labeling of rat endothelial cells is not uniform endothelial marker in all organs. Moreprecise investigation of these lectin reactive determinants in rat vascular endothelium, including developmentalchanges, isolation and enzyme-FACE sequencing of their carbohydrate moieties, generation of antibodiesand their possible organ specific binding affinities could give new insight into the physiological roleof GS I and HPA binding glycoproteins in rat endothelium.

Keywords: Lectin-gold probes, rat vascular endothelium, cellular heterogeneity