| Hypoxia-induced increases in pulmonary transvascular protein escape in rats. Modulation by glucocorticoids. | |
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MedLine Citation:
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PMID: 3198758 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Pulmonary edema after ascent to altitude is well recognized but its pathogenesis is poorly understood. To determine whether altitude exposure increases lung vascular permeability, we exposed rats to a simulated altitude of approximately 14,500 feet (barometric pressure [Pb] 450 Torr) and measured the pulmonary transvascular escape of radiolabeled 125I-albumin corrected for lung blood content with 51Cr-tagged red blood cells (protein leak index = PLI). Exposures of 24 and 48 h caused significant increases in PLI (2.30 +/- 0.08 and 2.40 +/- 0.06) compared with normoxic controls (1.76 +/- 0.06), but brief hypoxic exposures of 1-13 h produced no increase in PLI, despite comparable increases in pulmonary artery pressure. There were associated increases in gravimetric estimates of lung water in the altitude-exposed groups and perivascular edema cuffs on histologic examination. Normobaric hypoxia (48 h; fractional inspired oxygen concentration [FIO2] = 15%) also increased lung transvascular protein escape and lung water. Dexamethasone has been used to prevent and treat altitude-induced illnesses, but its mechanism of action is unclear. Dexamethasone (0.5 or 0.05 mg/kg per 12 h) started 12 h before and continued during 48 h of altitude exposure prevented the hypoxia-induced increases in transvascular protein escape and lung water. Hemodynamic measurements (mean pulmonary artery pressure and cardiac output) were unaffected by dexamethasone, suggesting that its effect was not due to a reduction in pulmonary artery pressure or flow. The role of endogenous glucocorticoid activity was assessed in adrenalectomized rats that showed augmented hypoxia-induced increases in transvascular protein escape, which were prevented by exogenous glucocorticoid replacement. In summary, subacute hypoxic exposures increased pulmonary transvascular protein escape and lung water in rats. Dexamethasone prevented these changes independent of reductions of mean pulmonary artery pressure or flow, whereas adrenalectomy increased pulmonary vascular permeability and edema at altitude. Increases in vascular permeability in hypoxia could contribute to the development of high-altitude pulmonary edema and endogenous glucocorticoids may have an important influence on pulmonary vascular permeability in hypoxia. |
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Authors:
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T J Stelzner; R F O'Brien; K Sato; J V Weil |
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Publication Detail:
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Type: Journal Article; Research Support, U.S. Gov't, P.H.S. |
Journal Detail:
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Title: The Journal of clinical investigation Volume: 82 ISSN: 0021-9738 ISO Abbreviation: J. Clin. Invest. Publication Date: 1988 Dec |
Date Detail:
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Created Date: 1989-01-20 Completed Date: 1989-01-20 Revised Date: 2013-03-26 |
Medline Journal Info:
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Nlm Unique ID: 7802877 Medline TA: J Clin Invest Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: 1840-7 Citation Subset: AIM; IM; S |
Affiliation:
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Cardiovascular Pulmonary Research Laboratory, University of Colorado Health Sciences Center, Denver 80262. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Adrenalectomy Altitude Sickness / etiology* Animals Anoxia / etiology*, metabolism* Capillary Permeability* Dexamethasone / pharmacology Extracellular Space / metabolism Glucocorticoids / pharmacology* Hemodynamics Male Methods Proteins / pharmacokinetics Pulmonary Circulation* Pulmonary Edema / etiology* Rats Rats, Inbred Strains |
| Grant Support | |
ID/Acronym/Agency:
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HL-01047/HL/NHLBI NIH HHS |
| Chemical | |
Reg. No./Substance:
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0/Glucocorticoids; 0/Proteins; 50-02-2/Dexamethasone |
| Comments/Corrections | |
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