ABSENCE OF ENHANCED INTIMAL THICKENING IN RESPONSE OF CAROTID ARTERIAL-WALL TO ENDOTHELIAL INJURY IN HYPERCHOLESTEROLEMIC RATS

  • 1 January 1976
    • journal article
    • research article
    • Vol. 35  (1) , 6-17
Abstract
Young male Sprague-Dawley rats fed a high cholesterol, thyroid-suppressive diet were subjected to drying injury of carotid artery endothelium; animals were sacrificed at various times up to 3 mo. after injury, and the vessels were examined by light, scanning and transmission EM. The diet induced marked elevation of serum cholesterol mainly present in lipoproteins of density < 1.063. The morphology and degree of intimal thickening in the injured carotids of such animals were compared with the changes found in control groups of normolipemic rats. In the control groups endothelium was completely regenerated between 7-14 days; intimal thickening was present at 14 days and at later stages and contained smooth muscle cells without lipid. In the cholesterol-fed animals endothelial regeneration and intimal thickening occurred as in the controls with the additional features: in the zone of intimal thickening in the injured segment, lipid was present in smooth muscle cells and, at later stages, in the extracellular matrix; undifferentiated mononuclear cells were noted in the thickened intima and, at 3 mo., were found adhering to normal and regenerated endothelium. No differences were found between control and hypercholesterolemic rats with respect to the degree of intimal thickening within the injured segment; enhancement of the smooth muscle proliferative response was not evident in the hypercholesterolemic rats. This form of hypercholesterolemia and its associated hyperlipoproteinemia may not be directly responsible for rat smooth muscle proliferation following endothelial denudation. Hyperlipemia may not necessarily cause persistence of myointimal hyperplasia in arteries.

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