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| Predicate | Object |
|---|---|
| rdf:type | |
| lifeskim:mentions | |
| pubmed:dateCreated |
1987-11-16
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| pubmed:abstractText |
1. Experiments were performed on isolated rat lungs perfused with Ringer solutions containing red cells. The goal was to clarify the role of active transport of Na+ for the absorption of fluid across the alveolar membrane, and to characterize active and passive pathways. 2. Partially degassed lungs were filled with 5 ml of an isotonic Ringer solution containing 125I-labelled albumin in order to calculate the fluid movement, and 22Na+ or 36Cl- for measurement of ion fluxes. Passive non-electrolyte permeability was determined in all experiments using [3H]mannitol. 3. The average rate of fluid absorption in phosphate-buffered instillates was 134 nl/s (S.E., 18.5; n = 14). With ouabain (10(-4) M) in the perfusate the fluid absorption rate fell to 57 nl/s (S.E., 8.2; n = 18). Amiloride (10(-3)-10(-4) M) in the instillate reduced the absorption to 75 nl/s (S.E., 8.6; n = 16). These results show that fluid absorption depends on transcellular transport of Na+ and that alveolar epithelial cells have a Na+ entry system in the luminal membrane and a Na+-K+ pump in the abluminal membrane. 4. The transcellular ion transport operates in parallel with a paracellular, passive leak that allows mannitol to pass with a permeability surface area product of 1.2 X 10(-4) ml/s, corresponding to a permeability coefficient of 2.4 X 10(-8) cm/s, assuming an alveolar surface area of 5000 cm2. 5. The passive fluxes of Na+ were 9.4 pmol/(cm2s) (S.E., 1.3; n = 25) in the direction from alveoli to perfusate and 8.0 pmol/(cm2s) (S.E., 0.86; n = 6) from perfusate to plasma. The passive fluxes of Cl- in the two directions were not significantly different either. Thus the transalveolar electrical potential difference is too small to affect ion movements measurably. 6. The passive permeability to Na+ was 6.7 X 10(-8) cm/s and to Cl- was 10.2 X 10(-8) cm/s (alveolar surface area assumed to be 5000 cm2). The ratio of the permeabilities is close to the ratio of the diffusion coefficients in free solution, suggesting a neutral or weakly charged paracellular channel. 7. We conclude that the alveolar epithelium performs solute-coupled fluid transport from alveoli to plasma, and that it shows many features that are common to other fluid-transporting epithelia; with an approximate surface area of 100 m2 in humans it constitutes one of the largest epithelial surfaces in the body.(ABSTRACT TRUNCATED AT 400 WORDS)
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| pubmed:commentsCorrections |
http://linkedlifedata.com/resource/pubmed/commentcorrection/3656149-1274636,
http://linkedlifedata.com/resource/pubmed/commentcorrection/3656149-14270570,
http://linkedlifedata.com/resource/pubmed/commentcorrection/3656149-216589,
http://linkedlifedata.com/resource/pubmed/commentcorrection/3656149-3116209,
http://linkedlifedata.com/resource/pubmed/commentcorrection/3656149-4055578,
http://linkedlifedata.com/resource/pubmed/commentcorrection/3656149-4443921,
http://linkedlifedata.com/resource/pubmed/commentcorrection/3656149-4581654,
http://linkedlifedata.com/resource/pubmed/commentcorrection/3656149-5647323,
http://linkedlifedata.com/resource/pubmed/commentcorrection/3656149-5775870,
http://linkedlifedata.com/resource/pubmed/commentcorrection/3656149-6149212,
http://linkedlifedata.com/resource/pubmed/commentcorrection/3656149-6258180,
http://linkedlifedata.com/resource/pubmed/commentcorrection/3656149-6869523,
http://linkedlifedata.com/resource/pubmed/commentcorrection/3656149-6881707,
http://linkedlifedata.com/resource/pubmed/commentcorrection/3656149-6947276,
http://linkedlifedata.com/resource/pubmed/commentcorrection/3656149-6964398,
http://linkedlifedata.com/resource/pubmed/commentcorrection/3656149-7039345,
http://linkedlifedata.com/resource/pubmed/commentcorrection/3656149-7118651,
http://linkedlifedata.com/resource/pubmed/commentcorrection/3656149-788989,
http://linkedlifedata.com/resource/pubmed/commentcorrection/3656149-9512,
http://linkedlifedata.com/resource/pubmed/commentcorrection/3656149-966267
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| pubmed:language |
eng
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| pubmed:journal | |
| pubmed:citationSubset |
IM
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| pubmed:chemical | |
| pubmed:status |
MEDLINE
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| pubmed:month |
Mar
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| pubmed:issn |
0022-3751
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| pubmed:author | |
| pubmed:issnType |
Print
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| pubmed:volume |
384
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| pubmed:owner |
NLM
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| pubmed:authorsComplete |
Y
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| pubmed:pagination |
311-24
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| pubmed:dateRevised |
2009-11-18
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| pubmed:meshHeading |
pubmed-meshheading:3656149-Absorption,
pubmed-meshheading:3656149-Amiloride,
pubmed-meshheading:3656149-Animals,
pubmed-meshheading:3656149-Biological Transport, Active,
pubmed-meshheading:3656149-Cell Membrane Permeability,
pubmed-meshheading:3656149-Chlorides,
pubmed-meshheading:3656149-Epithelium,
pubmed-meshheading:3656149-Lung,
pubmed-meshheading:3656149-Male,
pubmed-meshheading:3656149-Ouabain,
pubmed-meshheading:3656149-Pulmonary Alveoli,
pubmed-meshheading:3656149-Rats,
pubmed-meshheading:3656149-Rats, Inbred Strains,
pubmed-meshheading:3656149-Sodium,
pubmed-meshheading:3656149-Water
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| pubmed:year |
1987
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| pubmed:articleTitle |
Significance of active ion transport in transalveolar water absorption: a study on isolated rat lung.
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| pubmed:affiliation |
Département de Physiologie, Université Paris, France.
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| pubmed:publicationType |
Journal Article,
In Vitro
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