Intimal changes in the arteries of ageing swine

1. Twelve pigs between 4 and 10 years of age were examined for atherosclerosis of the aorta, coronary arteries, and other main arteries. Light- and electron-microscopy were used for study of the lesions. 2. All the pigs had intimal thickenings in the coronary arteries and aorta with a similar distribution to those of atherosclerosis in man. The structure of the thickenings showed many of the features of early human atherosclerotic lesions including changes in elastic tissue and accumulation of lipids, though the later complications found in human disease were not present. Similar lesions in other arteries were particularly well developed in the vessels supplying the mammary glands and uterus. 3. In general, the thickenings increased in extent and in histological development with increasing age. 4. The lipid content of the plasma and the lipid distribution in the high- and low-density lipoproteins were determined. The total plasma lipid concentrations were low when compared with those of man. In the females a higher proportion of the total plasma lipid was associated with the low-density lipoproteins than in most laboratory mammals, while in the two males examined the greater part of the plasma lipid was in the high-density fraction. 5. This investigation supports the idea that natural atherosclerosis in the pig is a suitable model for the experimental study of atherosclerosis in man.