| Critical capillary PO2 and the role of lactate production in oxyhemoglobin dissociation during exercise. | |
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MedLine Citation:
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PMID: 10659163 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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During exercise, O2 transport from capillary to myocyte is not diffusion-limited until end-capillary PO2 reaches its lowest value (critical capillary PO2). Critical capillary PO2 is reached at the mid-level of the subject's work capacity, not at Vo2 max. Femoral vein lactate does not increase until the critical capillary PO2 is reached. The increase in lactate is essential once the critical capillary PO2 is reached because the increase in H+ that accompanies the increase in lactate, through the "Bohr Effect", becomes the mechanism for oxyhemoglobin dissociation. Both normal subjects and patients with chronic stable heart failure have a critical capillary PO2 between 14 and 22 mm Hg. The pattern of femoral vein (end capillary) PO2 change as VO2 increases, describes the Vo2 at which O2 becomes diffusion limited and the extent to which new muscle capillary bed is recruited as Vo2 increases above the lactate threshold. |
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Authors:
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K Wasserman |
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Publication Detail:
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Type: Journal Article |
Journal Detail:
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Title: Advances in experimental medicine and biology Volume: 471 ISSN: 0065-2598 ISO Abbreviation: Adv. Exp. Med. Biol. Publication Date: 1999 |
Date Detail:
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Created Date: 2000-04-11 Completed Date: 2000-04-11 Revised Date: 2004-11-17 |
Medline Journal Info:
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Nlm Unique ID: 0121103 Medline TA: Adv Exp Med Biol Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: 321-33 Citation Subset: IM |
Affiliation:
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Division of Respiratory and Critical Care Physiology and Medicine, Harbor-UCLA Medical Center, UCLA School of Medicine, Torrance 90509, USA. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Acidosis, Lactic
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metabolism Adult Blood Gas Analysis Buffers Capillaries / metabolism Cardiac Output, Low / metabolism* Exercise / physiology* Femoral Vein / metabolism Humans Lactic Acid / biosynthesis* Oxygen / metabolism* Oxyhemoglobins / metabolism* |
| Chemical | |
Reg. No./Substance:
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0/Buffers; 0/Oxyhemoglobins; 50-21-5/Lactic Acid; 7782-44-7/Oxygen |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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