Atherosclerosis in the hypercholesterolemic hare. Comparison of coronary artery lesions induced by dietary cholesterol in the hare and the rabbit.

Atherosclerotic lesions in coronary arteries were compared in 10 hybrid hares and 14 rabbits after induction of hypercholesterolemia, using a cholesterol-enriched diet. All proximal portions of hare coronary arteries contained intimal lesions, often with severe luminal stenosis. These lesions were characterized by the presence of foam cells, smooth muscle cells, and areas of atheronecrosis. Foam cells were also found focally in the media. As part of the intimal changes, iron deposition was present in 65% and calcification was present in 32.5% of proximal segments examined. The proportion of segments with intimal lesions and the intima/media cross-sectional area ratios (I/M ratios) were greatest in proximal segments with stepwise decreases in the mid and distal segments. As area of myocardial infarction was present in one hare. In contrast, 46.5% of proximal segments of rabbit coronary arteries had no intimal lesions and those lesions present had no calcium or iron deposition. No infarction was observed in rabbit hearts. The proportion of segments with lesions and the mean I/M ratios were significantly greater in the hare than the rabbit, with proximal and mid coronary segments showing the most marked differences. The hare appears to develop coronary artery lesions more like those seen in man, with high grade, proximal stenoses occurring uniformly in hypercholesterolemic animals. In contrast, the atherosclerosis developing in rabbit coronary arteries is less uniform and includes involvement of intramyocardial arterioles. The hare offers several advantages as a model of human atherosclerosis.