Abstract
Hypoxia produces muscularization of the peripheral normally non-muscular regions of pulmonary artery. In addition, medial thickening is found in the large already muscular arteries and is known to be associated, in certain congenital heart diseases, with narrowing of internal lumen diameter.
The present study traces the development of increased wall thickness in the muscular pulmonary artery at the hilum, seen in rats with hypoxia-induced pulmonary hypertension. Hypertension was produced by exposure to half an atmosphere for 1-52 days. For this study, arteries and airways were distended and fixed with glutaraldehyde using a simultaneous injection technique. All coats of the pulmonary artery are affected. The first change is apparent from Day 3, hypertrophy of endothelial cells and adventitial fibroblasts with increased connective tissue, all leading to thickening of the coats. By Day 7, the medial coat also is increased, due at first to hypertrophy of smooth muscle cells and later to increased connective tissue. Uptake of 3H-thymidine shows an early and marked increase in mitotic activity of fibroblasts and endothelial cells but smooth muscle cells show little increase. On removal from hypoxia, wall thickness decreases but lumen diameter does not increase.
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Meyrick, B., Reid, L. 1207 STRUCTURAL FEATURES OF CONTINUED HYPOXIA ON LARGE PULMONARY ARTERIES OF RAT. Pediatr Res 12 (Suppl 4), 565 (1978). https://doi.org/10.1203/00006450-197804001-01213
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DOI: https://doi.org/10.1203/00006450-197804001-01213