Effect of repeated endotoxin treatment and hypercholesterolemia on preatherosclerotic lesions in weaned pigs. Part 1. Scanning and transmission electron microscopic study.

Endothelial cell damage is considered to be the primary event in atherogenesis. In this study we compared the effects of mild hypercholesterolemia and repeated E. coli endotoxin infusions on the endothelial cells of the coronary arteries of the pig. We divided 24 pigs into 4 groups: I: controls on normal diet; II: normal diet and endotoxin treatment; III: fat-supplemented diet; IV: fat-supplemented diet and endotoxin treatment. The animals on a fat-supplemented diet showed the most frequent and most severe endothelial cell damage. The damage was less when this diet was combined with endotoxin treatment. Endotoxin reduced the serum total cholesterol level (P less than 0.01). The cholesterol level correlated very significantly (P less than 0.001) with endothelial damage of the coronary arteries. Mild hypercholesterolemia (s-cholesterol 5.68 mmol/l, controls 2.28 mmol/l) was thus associated with toxic effects in the endothelial cells. The E. coli endotoxin infusions did not have any cumulative effect on the lesions.