The liquid layer lining the alveoli in the lung has been difficult to study because of its thinness, inaccessibility, and high water content. The electron microscope could magnify the alveolar lining sufficiently but its vacuum required that water be removed and the attendant shrinkage and distortion of this highly-hydrated layer made analysis problematic. With the advent of the low-temperature scanning electron microscope, lung can be analyzed at magnifications of 10 to 10,000X with water preserved as ice in the frozen hydrated state. The native air-liquid interface in the alveoli thus can be imaged directly. The proposed study will test several hypotheses: 1) That the surface lining layer is continuous over the entire alveolus and indeed over the entire alveolar duct portion of the respiratory zone will be shown by examining microdissections of airways in frozen hydrated rat lungs at high magnification. 2) That the contour of the surface is smooth will be tested by applying surface roughness criteria to stereo images of hydrated alveoli. 3) The thickness and volume of the aqueous subphase of the alveolar lining layer will be determined with photogrammetric methods from 3-dimensional images made with the low- temperature scanning electron microscope. 4) That all pores of Kohn are filled with alveolar lining material in normal lungs will be tested by counting the number of open pores in hydrated, frozen alveoli. Studies will be extended to human normal and emphysematous lung. Characterization of the alveolar lining layer is important in understanding the contribution of surface forces to the mechanics of respiration and for preventing and treating conditions that are disturbances of this layer such as the Respiratory Distress Syndrome, Pulmonary Edema and Pneumonia.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL040521-04
Application #
3357736
Study Section
Pathology A Study Section (PTHA)
Project Start
1988-04-01
Project End
1993-03-31
Budget Start
1991-04-25
Budget End
1992-03-31
Support Year
4
Fiscal Year
1991
Total Cost
Indirect Cost
Name
Lawrence Berkeley National Laboratory
Department
Type
Organized Research Units
DUNS #
078576738
City
Berkeley
State
CA
Country
United States
Zip Code
94720
Bastacky, J; Lee, C Y; Goerke, J et al. (1995) Alveolar lining layer is thin and continuous: low-temperature scanning electron microscopy of rat lung. J Appl Physiol 79:1615-28
McCray Jr, P B; Bettencourt, J D; Bastacky, J (1992) Secretion of lung fluid by the developing fetal rat alveolar epithelium in organ culture. Am J Respir Cell Mol Biol 6:609-16
Bischof, J C; Bastacky, J; Rubinsky, B (1992) An analytical study of cryosurgery in the lung. J Biomech Eng 114:467-72
McCray Jr, P B; Reenstra, W W; Louie, E et al. (1992) Expression of CFTR and presence of cAMP-mediated fluid secretion in human fetal lung. Am J Physiol 262:L472-81
Lewis, E R; Hecht, E I; Narins, P M (1992) Diversity of form in the amphibian papilla of Puerto Rican frogs. J Comp Physiol A 171:421-35
McCray Jr, P B; Bettencourt, J D; Bastacky, J (1992) Developing bronchopulmonary epithelium of the human fetus secretes fluid. Am J Physiol 262:L270-9
Bastacky, J; Goerke, J (1992) Pores of Kohn are filled in normal lungs: low-temperature scanning electron microscopy. J Appl Physiol 73:88-95
Yager, D; Butler, J P; Bastacky, J et al. (1989) Amplification of airway constriction due to liquid filling of airway interstices. J Appl Physiol 66:2873-84