ABDOMINAL AORTIC-ANEURYSMS ARE ASSOCIATED WITH ALTERED MATRIX PROTEINS OF THE NONANEURYSMAL AORTIC SEGMENTS

Purpose: Abdominal aortic aneurysms (AAA) are associated with diffuse arteriomegaly and peripheral aneurysms, suggesting a generalized proce ss. Elastin and collagen are the key structural proteins of the aorta, and their relative content is markedly altered in tissue from AAA. Ou r purpose was to investigate elastin and collagen content in the proxi mal, nonaneurysmal segments of aortas with infrarenal AAA. Methods: Af ter extraction of lipid, calcium, and soluble proteins, hydroxyproline (collagen) and desmosine-isodesmosine (elastin) contents were determi ned by high-performance liquid chromatography in the ascending and des cending thoracic, supraceliac, and suprarenal aorta. By repeated measu res of analysis of covariance, collagen was found to be increased thro ughout the aorta in AAA as compared with normal aorta or aorta with at herosclerotic occlusive disease. This difference remained significant when adjustments were made for group differences in age and degree of atherosclerosis. This increase in collagen content results in a diluti onal decrease in elastin concentration. These data demonstrate that th e same matrix protein alterations found in AAA tissue occur throughout the aorta, differing only in magnitude in the aneurysmal and nonaneur ysmal segments. These data suggest that aneurysm formation may relate to alterations in the regulation of elastin and collagen.