Contributions of Elastin and Collagen Organization to Passive Mechanical Properties of Arterial Tissue
This chapter identifies contributions of elastin and collagen organization to the mechanical properties of tissue fabric. A wide mechanical repertoire is met by complementary anatomic and biophysical properties of three fibrous proteins: actin-myosin of smooth muscle cells, elastin of the elastic membranes, and the collagens in fibers and bundles of the medial and adventitial layers. The three fibrous proteins are anatomically and functionally linked into a tissue fabric. Studies of the passive mechanical properties of arteries in vitro using the elastomeric approach of force-deformation analyses began with the work of C. S. Roy, A. C. Burton, and D. H. Bergel. Collagen synthesis and extracellular organization into fibers and bundles and subsequent aging are multi-stepped processes. As collagen synthesis and accumulation begin, the most common crosslinks are the dehydro forms of hydroxylysinonorleucine and histidinohydroxymerodesmosine. Most of the crosslinks identified with the initial steps of collagen fiber and bundle formation are chemically unstable and their levels decline with more advanced collagen organization.