Increased DNA replication in the arterial adventitia after aortic ligation

Abstract

After microsurgical dissection of the thoracic aorta of normotensive rats, biochemical and morphological comparisons were performed between the intima-media and adventitia. The DNA content, wet weight, and dry defatted weight of the adventitia were half that of the intima-media. Collagen was the main component of the adventitia (collagen > nonfibrous protein > elastin) whereas elastin was the main protein in the intima-media (elastin > nonfibrous protein > collagen), and the results correlated with morphological observations. Hypertension induced by aortic ligation between the renal arteries resulted in rapid elevations in circulating humoral factors and blood pressure. A sixfold increase in DNA synthesis was observed in the adventitia (p < 0.001), resulting in a significant increase in DNA content as early as 6 days after aortic ligation (75% increase; p < 0.001). Increased DNA replication was accompanied by elevations hi nonfibrous protein and elastin contents. Autoradiograms showed labeled adventitia] fibroblasts throughout the thickness of the adventitia and along the entire length of the aorta and smaller vessels. DNA synthesis and content and labeled smooth muscle cells were increased hi the intima-media. These studies indicate that the adventitia participates hi the development of vascular hypertrophy and arterial disease produced by aortic ligation. © 1988 American Heart Association, Inc.