Estimation of diffusive and convective macromolecular transport through the capillary-alveolar barrier by bronchoalveolar lavage

Emeriaud, G.; Bayat, S.; Briot, R.; Grimbert, F.; Martiel, J.L.uis

FASEB Journal 18(4-5): Abstract 218


ISSN/ISBN: 0892-6638
Accession: 034871790

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In previous studies, (1,2) we used a series of broncho-alveolar lavages in anesthetized dogs to estimate the lung epithelial lining fluid volume and the capillary-alveolar barrier permeability to macromolecules. To assess the mechanisms underlying exchanges between blood and the lung lavaged segment, a bi-compartmental model was designed in which both convective and diffusive fluid and molecule fluxes were considered. Using the experimentally known fluid fluxes between the syringe and the fiberoptic bronchoscope and the lavaged lung segment, we were able to estimate the convective fluid flux between blood and lung. The convective flux of macromolecules (70kD dextrans) was estimated from the convective water fluid and macromolecule concentration measurements in the lung segment. The analysis of the experimental data suggests that the model is compatible with the data and accounts for the experimental results. In addition, the model provides a numerical estimation of the diffusive (theta) and reflective (sigma) transport coefficients (from blood to lung) of macromolecules through the capillary-alveolar barrier. 1 S. Bayat et al. (1998). Am. J. Respir. Crit. Care Med. 158:1715-1723.2 S. Bayat et al. (2000) Crit. Care Med. 28(8):2937-2942.Results are given in the table below.m +/- SE theta (min-1) sigmaControl (n=35) 0.0030+/-0.0004 0.872+/-0.030Oleic acid injury (n=17) 0.120+/-0.006 0.353+/-0.0903Supported by a grant of MinistEre de la Recherche et de la Technologie (RNTS).