HYPOXIA AND INCORPORATION OF THYMIDINE-H-3 BY CELLS OF THE RAT PULMONARY-ARTERIES AND ALVEOLAR WALL

  • 1 January 1979
    • journal article
    • research article
    • Vol. 96  (1) , 51-70
Abstract
Hypoxia produces increase in thickness of the medial muscle coat and the adventitia; of the pulmonary arteries and muscle appears in smaller arteries than is normal and the number of small arteries that fill on Micropaque-gelatin contrast medium injection is reduced. The uptake of 3H-thymidine by the pulmonary arterial wall cells was measured in rats exposed to hypobaric hypoxia (exposure to 380 torr) after 1, 3, 5, 7, 10 and 14 days to study its effect on hyperplasia. Using autoradiographs of 1-.mu.m sections, the glutaraldehyde-distended intrapulmonary hilar muscular artery, the peripheral, intraacinar arteries less than 100 .mu.m in external diameter and the alveolar wall had different patterns of uptake. In the hilar pulmonary artery, after 24 h of exposure, the labeling index for adventitial fibroblasts increased 8-fold over the control value, for endothelial cells, 3-fold, and for medial smooth muscle cells, there is a gradual and small increase to day 14. Newly muscularized intraacinar arteries are 1st apparent at day 3, when they comprise 40% of the intraacinar arteries, increasing to 80% at day 7. Density of arteries did not decrease. Uptake of 3H-thymidine by new muscle cells is not apparent until day 5 when labeling is maximum. The endothelial cells of the newly muscularized arteries show an increased labeling index only at days 7 and 10. The veins and normally muscular arteries do not show these changes. In the alveolar walls, the concentration of labeled cells is significantly above the control value at days 3, 5 and 7 and significantly below, at day 14. Interstitial, epithelial and endothelial cells contribute to the increase.