Proteoglycan distribution in catheter-induced aortic lesions in normolipaemic rabbits. An ultrastructural study.

The aortic lesions induced in normal-fed rabbits by an indwelling catheter were examined for changes in lipid content shown by oil red O-stained sections and associated proteoglycan distribution and ultrastructural changes by transmission electron microscopy of ruthenium red-stained sections, during an 8-week period of regression. Compared to normal aorta there was a highly significant increase in proteoglycan in lipid-containing lesions, which was also associated with the presence of regenerated endothelium. In the lesions which had regressed in terms of size and lipid content, the proteoglycan concentration, especially in superficial regions, was significantly reduced compared to early lesions and was similar to that seen in the normal vessel. Proteoglycan concentration decreased before lipid content of lesions was reduced. Proteoglycan was not associated with lipid-containing macrophages. These observations support the hypothesis that an increased glycosaminoglycan concentration is associated with lipid deposition in the vessel wall in response to injury in the absence of hyperlipaemia.