Functional diameters of alveolar microvessels at high lung volume in zone II

• Published in: Journal of applied physiology (1985) 1998-07, Vol.85 (1), p.47-52
• Main Authors: Conhaim, Robert L, Rodenkirch, Lance A
• Format: Article
• Language: English
• Subjects: Air breathing; Animals; Biological and medical sciences; Blood vessels; Capillaries - anatomy & histology; Fundamental and applied biological sciences. Psychology; Image Processing, Computer-Assisted; Lung - anatomy & histology; Lungs; Male; Microscopy, Confocal; Microspheres; Particle Size; Pulmonary Alveoli - anatomy & histology; Pulmonary Alveoli - blood supply; Pulmonary Circulation - physiology; Rats; Respiratory system: anatomy, metabolism, gas exchange, ventilatory mechanics, respiratory hemodynamics; Rodents; Vertebrates: respiratory system
• ISSN: 8750-7587; 1522-1601
• DOI: 10.1152/jappl.1998.85.1.47

Department of Surgery, University of Wisconsin-Madison, Madison, Wisconsin 53705 To estimate the functional diameter of alveolar microvessels, we perfused isolated rat lungs with fluorescent latex particles (1 diameter/lung) at inflation, pulmonary arterial, and left atrial pressures of 25, 30, and 0 cmH 2 O, respectively. We used confocal microscopy to count latex particles within septal microvessels and flow cytometry to count particle concentrations in venous outflow. We found 1-, 2-, and 4-µm-diameter particles within septal vessels of 45 ± 12, 31 ± 12, and 25 ± 9%, respectively, of examined alveoli. Particles of 5-µm diameter were absent from septal vessels but were present within a small percentage of corner vessels. Particle concentrations in the venous outflow for 1-, 2-, 4-, and 5-µm-diameter particles were 54 ± 28, 67 ± 32, 2.2 ± 0.3, and 0.4 ± 0.3%, respectively, of the arterial inflow. Particles with diameters of 6 or 10 µm were absent from venous outflow. Our results suggest that, under these conditions, the functional diameter of the septal microvessels is ~4 µm and that the diameter of the adjacent corner vessels is slightly larger but