Collagen synthesis in organ culture of normal and atherosclerotic aortas.

Using pulse-label experiments in organ culture, collagen synthesis was studied in aortas from healthy and atherosclerotic specimens. Investigations were carried out on human atherosclerotic plaques as well as in the mini-pig in which atherosclerosis occurred spontaneously, and in the rabbit where atherosclerosis was experimentally induced by cholesterol-enriched feeding. When compared to total protein synthesis, the percentage of newly synthesized collagens measured as radioactive pepsin-resistant material, decreased with age in healthy specimens, whereas it remained at a higher level when the aortas were atherosclerotic. Subsequent molecular sieve chromatography of the radioactivity pepsin-resistant material allowed the separation type I collagen from type III collagen and their relative quantification. The results showed that the newly synthesized type III collagen accounted for 16-31% in aortic explants from young animals, for 30-36% when the explants were derived from older specimens and for 35-48% when the tissues were atherosclerotic.