| Influence of proton availability on intracapillary CO2-HCO3(-)-H+ reactions in isolated rat lungs. | |
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MedLine Citation:
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PMID: 1321108 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Transcapillary CO2 exchange entails a transient perfusate CO2-HCO3(-)-H+ disequilibrium, leading to net loading or unloading of blood HCO3-. Perfusate reequilibration may or may not reach completion during the time of capillary transit, depending on the rate of intracapillary CO2-HCO3(-)-H+ reactions. Failure to reestablish equilibrium within the "open" capillary system leads to continued reequilibration in the "closed" postcapillary vasculature with resultant shifts in postcapillary perfusate PCO2, pH, and [HCO3-]. In the present study, we determined the effects of perfusate nonbicarbonate buffer capacity (beta) on intracapillary CO2-HCO3(-)-H+ reactions in isolated saline-perfused rat lungs. Effects of beta on the rate of transcapillary CO2 excretion (VCO2) and the magnitude of the postcapillary perfusate pH disequilibrium were measured as a function of luminal vascular carbonic anhydrase (CA) activity. The data indicate that beta markedly influenced the kinetics and dynamics of intravascular CO2-HCO3(-)-H+ reactions. beta affected VCO2 and the relative enhancement of VCO2 by luminal vascular CA. The data emphasize the inadequacies of using traditional "equilibrium" models of the CO2-HCO3(-)-H+ system to investigate capillary CO2 transport and exchange, even in organs (e.g., lungs) that contain significant luminal vascular CA activity. |
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Authors:
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T A Heming; A Bidani |
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Publication Detail:
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Type: In Vitro; Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: Journal of applied physiology (Bethesda, Md. : 1985) Volume: 72 ISSN: 8750-7587 ISO Abbreviation: J. Appl. Physiol. Publication Date: 1992 Jun |
Date Detail:
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Created Date: 1992-08-19 Completed Date: 1992-08-19 Revised Date: 2006-11-15 |
Medline Journal Info:
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Nlm Unique ID: 8502536 Medline TA: J Appl Physiol Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: 2140-8 Citation Subset: IM |
Affiliation:
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Department of Internal Medicine, University of Texas Medical Branch, Galveston 77550. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Animals Bicarbonates / metabolism Buffers Capillaries / metabolism Carbon Dioxide / metabolism* Carbonic Anhydrases / metabolism Hydrogen-Ion Concentration Kinetics Lung / blood supply, metabolism* Male Perfusion Protons Pulmonary Gas Exchange / physiology* Rats Rats, Inbred Strains |
| Chemical | |
Reg. No./Substance:
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0/Bicarbonates; 0/Buffers; 0/Protons; 124-38-9/Carbon Dioxide; EC 4.2.1.1/Carbonic Anhydrases |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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