AGE-RELATED ALTERATION OF CROSS-LINKING AMINO-ACIDS OF ELASTIN IN HUMAN AORTA

It is well known that the elastic property of human aorta decreases gr adually with age. Since the cross-linking structures are responsible f or this elasticity, age-related changes of cross-linking amino acids i n human aorta were studied using a high-performance liquid chromatogra phy (HPLC). Non-atherosclerotic areas of thoracic aorta of 27 autopsy cases which had no particular aortic disease mere obtained. After acid hydrolysis, SEP-PAKT(TM) silica-gel column and Fe3+/activated charcoa l column pretreatment were carried out for analysis of desmosine (DES) , isodesmosine (ISDES), neodesmosine (NEO), oxodesmosine (OXO) and iso oxodesmosine (ISOXO), and for analysis of aldosine (ALD), respectively . These prepared samples were applied to the reversed-phase HPLC colum n. We also analyzed pyridinoline (PYR), a major cross-linking amino ac id of collagen as an index of fibrosis. All cross-linking amino acids of elastin rapidly increased in infancy and then gradually decreased w ith age. In the middle- and old-age, the amount of OXO showed marked v ariety. PYR was little detected at 0 year-old, and then gradually incr eased with age. The crosslinks of elastin were rapidly formed in child hood and then decreased with age. These findings suggest that the rela tive increase of NEO, OXO or ISOXO to DES and ISDES is associated with age-related weakening and/or damage of elastin, and that the gradual shift from elastin- to collagen-dominant state is a possible cause of the loss of elasticity and the gain of stiffness in the aging aorta.