Relative efficiency of incorporation of newly synthesized elastin and collagen into aorta, pulmonary artery and pulmonary vein of growing pigs.

It is generally accepted that, once laid down in the extracellular matrix, elastin turns over only very slowly if at all. However, much of the evidence for minimal turnover of elastin comes from aortic tissue. In this study we have compared the relative synthesis rates of elastin and collagen with their relative accumulation rates in segments of aorta (AO), pulmonary artery (PA), and pulmonary vein (PV) of young, growing pigs. While rates of elastin synthesis are comparable in the AO and PA, the PA accumulates only 33% of the elastin deposited in the AO. Similarly, while the rate of elastin synthesis in the PV is 60% of that in the AO, accumulation of elastin is only 20% of that in the AO. Similar discrepancies between collagen synthesis and accumulation were seen among these three vessels. These data suggest that, at least in growing animals, the efficiency of permanent incorporation of elastin and collagen into the extracellular matrix may be an important factor in determining the final contents of these connective tissue proteins in vascular tissues.