"Spontaneous" endothelial injury and lipid accumulation in the rat caudal artery.

We have studied the role of endothelial injury and subsequent repair in the accumulation of plasma lipids within lesions of the rat caudal artery where spontaneous endothelial damage occurs. Lesions from diet-induced hypercholesterolemic rats were classified both according to the morphology of their luminal cell covering and the extent of medial lipid deposits. Lesions covered with regenerating and newly regenerated cells accumulated more lipids than deendothelialized lesions or those covered with cells resembling normal endothelium, which suggests that the lipid accumulation consecutive to spontaneous endothelial injury occurs during the early phase of repair. In addition, lesions located in the distal part of the artery accumulated less lipids than those in the proximal part, although endothelial damage occurred with equal frequency in both locations. This suggests that even in the presence of severe hypercholesterolemia, favorable local conditions are required in addition to endothelial injury for maximal arterial lipid accumulation to occur.