Induction of Increased Collagen and Elastin Biosynthesis in Copper-Deficient Pig Aorta.
Hill, Kenneth E.; Davidson, Jeffrey M.
6(1):98-104, January/February 1986.
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Young pigs raised on a copper-deficient diet develop severe abnormalities of connective tissue due to defective cross-linking of collagen and elastin. They eventually succumb to anemia and cardiovascular damage, the latter apparently due to the defective connective tissue metabolism. We evaluated the effects of nutritional copper deficiency upon collagen and elastin synthesis using short-term explant cultures of the medial portion of four successive segments of the descending aorta from 110- day-old pigs raised on a copper-deficient diet. Collagen synthesis was evaluated by collagenase susceptibility, and elastin synthesis was quantified by immunoprecipitation with an antiporcine-elastin antiserum. In the normal developing aorta, elastin synthesis was maximal in the upper thoracic aorta, while levels of collagen synthesis were highest in the lower abdominal aorta. Both activities subsided by 110 days postpartum. Compared with controls, the copper-deficient group showed: 1) histopathologic changes confined to the luminal half of the thoracic aorta; 2) a 1.3- to 1.6- fold increase in cellularity along the entire length of the organ; 3) a 1.3- to 2.4-fold increase in relative collagen synthesis, the greatest change occurring in the thoracic portion; 4) a 3- to 4-fold increase of relative elastin synthesis in the thoracic aorta, the abdominal aorta remaining unchanged; 5) 4- to 10-fold increases in collagen production; and 6) a greater than 15-fold increase in elastin production by the tissue of the thoracic aorta. Although copper deficiency produced a complex set of alterations, the combination of defective cross-linking, hypertension, and increased cardiac output appeared to be responsible for the hyperplasia of vascular smooth muscle and a striking induction of connective tissue production. These effects may represent an authentic compensatory mechanism.
(C) 1986 American Heart Association, Inc.