Local changes in collagen content in rabbit aortic atherosclerotic lesionswith time

A video-microdensitometry method was used to quantify collagen on a pixel b y pixel basis at specific locations within atherosclerotic lesions, induced by feeding New Zealand White rabbits a declining cholesterol diet. Probabi lity mapping (done previously) showed the lesions occurred in predictable l ocations so the age of any one area of a lesion could be estimated. The old est part of the lesion was on the lateral lip of the flow divider as lesion s always developed there first. Serial sections through three lesions showe d the distribution of collagen within the plaque. The measurement of all th e lesions showed that early lesions had low collagen levels: 3-6% for the i ntercostals and 8-11% for the renals. Collagen increased consistently with time on the diet to 11-15% for the intercostal and approximate to 17% for t he renal. The aorto-renal lesions were more severe; thicker and with a high er percentage of collagen. The greatest collagen content was on the lateral lip of the how dividers, where controls had intimal thickening. No fibrous caps were seen. This study shows conclusively that collagen is not evenly distributed in lesions, but develops progressively in specific locations of fatty plaques with the duration of cholesterol feeding. Intimal thickening predisposes to early collagen development. (C) 1999 Elsevier Science Irela nd Ltd. An rights reserved.