Age dependent biochemical changes in dermal connective tissue. Relationship to histological and ultrastructural observations.

A biochemical study of skin biopsies of young normal subjects and two groups of aged subjects, one active and the other confined to bed, was made and the results compared with histological observations. Skin biopsies were incubated with 3H proline and 14C glucosamine and connective tissue components were sequentially extracted. In each extract the specific activity of total and collagenous protein was determined. With age a decrease was observed in both the amount of protein and the 3H proline incorporation of collagenous extracts. A parallel increase in 14C glucosamine incorporation was also noticed in extracts containing glycosaminoglycans and structural proteins. These results agree in part with the changes observed by light and electron microscopy, which revealed an increase in ground substance and fragmentation of collagen bundles in the dermis of older subjects.