THE OCCURRENCE OF ATHEROMATOUS LESIONS IN THE CORONARY ARTERIES OF RATS

Abstract

1. Spontaneous atherosclerosis in the coronary arteries of the normal rat is reported. The incidence and severity of the lesion increases with age, and occurred in over 60 per cent of the rats more than 500 days old. 2. Groups of rats were fed synthetic diets containing 16 per cent palm kernel oil, groundnut oil, palm oil, and butterfat from the age of 5–10 weeks until death between 330 and 600 days. The incidence and structure of the atheromatous lesions in the coronary arteries was similar to that in the animals on stock diet. 3. The atheromatous lesions consisted of fibrous thickenings of the intima producing plaques which consisted mainly of collagenous tissue, swollen endothelial cells and some hyaline material. Fat was distributed throughout the plaques in the form of fine droplets. 4. The possibility that the mechanism of atheromatous plaque formation in the coronary arteries of normal animals may be different from that in experimental animals in which there is marked hyperlipæmia, and the advantages of using the rat as an experimental animal in the investigation of atherosclerosis, are discussed.