ASSOCIATION OF HYALURONAN WITH RAT VASCULAR ENDOTHELIAL AND SMOOTH-MUSCLE CELLS

We investigated the distribution of hyaluronan (hyaluronic acid) in ra t vascular tissue fixed by an osmium tetroxide (or glutaraldehyde) mic rowave technique and embedded in epoxy resin (or Lowicryl K4M), using hyaluronan binding proteins coupled to 15-20-nm gold particles as ultr astructural markers in a one-step post-embedding procedure. The intra- and extracellular aspects of vascular endothelial and smooth muscle c ell plasma membranes revealed distinct labeling, with a high affinity for caveolae being manifested in both cell types and in all kinds of v essels. Hyaluronan was also localized intercellularly in areas charact erized by extensive endothelial cell interdigitation. Intracellularly, moderate staining of nuclear heterochromatin was observed.