Morphometry of the subepithelial circulation in sheep airways. Effect of vascular congestion.
In order to quantitate the subepithelial microvascular volume and its relation to the airway lumen, we conducted a morphometric analysis of the vascular compartment in the wall of the trachea (within a 55-microns depth from the epithelial basement membrane) and of 1.0 and 0.5-mm bronchioles of sheep. The lungs were fixed by bronchial and pulmonary artery perfusion with glutaraldehyde under three experimental conditions: (1) bronchial artery pressure, 100 mm Hg pulmonary artery pressure, 20 mm Hg (control); (2) bronchial artery pressure, 100 mm Hg, pulmonary artery pressure, 40 mm Hg (pulmonary hypertension, PH); (3) bronchial artery pressure, 100 mm Hg, pulmonary artery pressure, 40 mm Hg (pharmacologic vasodilation with sodium nitroprusside, PH + V). Venous pressures were atmospheric. Under control conditions, the microvascular volume fraction comprised 12, 16, and 15% of the subepithelial tissue in the trachea and 1-mm and 0.5-mm bronchioles, respectively. PH increased the microvascular volume fraction in the bronchioles (p less than 0.05), but it had no effect on the microvasculature in the trachea. PH + V approximately doubled the microvascular volume fraction in the trachea and the bronchioles. PH increased the mean wall thickness, and PH and PH + V decreased the airway cross-sectional area in the 1-mm bronchioles. These observations demonstrate that the microvasculature constitutes a considerable volume fraction of the subepithelial airway tissue and that vascular congestion can narrow the bronchiolar lumen.
Mariassy
A T
AT
Pulmonary Division, University of Miami, Florida.
Gazeroglu
H
H
Wanner
A
A
D000818:Animals; D001160:Arterioles / Q000473:pathology; D001980:Bronchi / Q000098:blood supply*; D002196:Capillaries / Q000473:pathology; D004848:Epithelium / Q000098:blood supply; D005260:Female; D006976:Hypertension, Pulmonary / Q000473:pathology* / Q000503:physiopathology; D009599:Nitroprusside / Q000494:pharmacology; D012756:Sheep; D014132:Trachea / Q000098:blood supply*; D014664:Vasodilation / Q000187:drug effects; D014699:Venules / Q000473:pathology
D009599:Nitroprusside