Cyclic stretching stimulates synthesis of matrix components by arterial smooth muscle cells in vitro

Rabbit aortic medial cells were grown on purified elastin membranes, which were then subjected to repeated elongation and relaxation or to agitation without stretching. Cells remained attached to the membranes, and cyclic stretching resulted in a two- to fourfold increase in rates of collagen, hyaluronate, and chondroitin 6-sulfate synthesis over those in agitated or stationary preparations. Synthesis of types I and III collagen was increased to the same degree. Stretching did not increase rates of chondroitin 4-sulfate or dermatan sulfate synthesis. Differences were not attributable to differences in cell number, for DNA synthetic rates were not increased by stretching. The model system devised to demonstrate these effects provides a means for relating various modes of mechanical stimulation to cell metabolism.

Localization of antigenic determinants in the polypeptide chains of collagen

After being injected with collagen from rat or guinea pig skin, rabbits form high titer, species-specific antibodies to collagen. Antibody is directed primarily against the alpha2 chain of collagen with little reaction with the alpha1 chain. The amino terminal peptide of cyanogen bromide cleavage of the alpha2 chain of guinea pig skin collagen, alpha2-CBl, effectively inhibited the antigen-antibody reaction, an indication that a major antigenic determinant of collagen is located at the amino terminal of the alpha2 chain.