Document Detail


Metabolic component of intestinal PCO(2) during dysoxia.
MedLine Citation:
PMID:  11090598     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The adequacy of intestinal perfusion during shock and resuscitation might be estimated from intestinal tissue acid-base balance. We examined this idea from the perspective of conventional blood acid-base physicochemistry. As the O(2) supply diminishes with failing blood flow, tissue acid-base changes are first "respiratory, " with CO(2) coming from combustion of fuel and stagnating in the decreasing blood flow. When the O(2) supply decreases to critical, the changes become "metabolic" due to lactic acid. In blood, the respiratory vs. metabolic distinction is conventionally made using the buffer base principle, in which buffer base is the sum of HCO(3)(-) and noncarbonate buffer anion (A(-)). During purely respiratory acidosis, buffer base stays constant because HCO(3)(-) cannot buffer its own progenitor, carbonic acid, so that the rise of HCO(3)(-) equals the fall of A(-). During anaerobic "metabolism," however, lactate's H(+) is buffered by both A(-) and HCO(3)(-), causing buffer base to decrease. We quantified the partitioning of lactate's H(+) between HCO(3)(-) and A(-) buffer in anoxic intestine by compressing intestinal segments of anesthetized swine into a steel pipe and measuring PCO(2) and lactate at 5- to 10-min intervals. Their rises followed first-order kinetics, yielding k = 0. 031 min(-1) and half time = approximately 22 min. PCO(2) vs. lactate relations were linear. Over 3 h, lactate increased by 31 +/- 3 mmol/l tissue fluid (mM) and PCO(2) by approximately 17 mM, meaning that one-half of lactate's H(+) was buffered by tissue HCO(3)(-) and one-half by A(-). The data were consistent with a lumped pK(a) value near 6.1 and total A(-) concentration of approximately 30 mmol/kg. We conclude that the respiratory vs. metabolic distinction could be made in tissue by estimating tissue buffer base from measured pH and PCO(2).
Authors:
O Raza; R Schlichtig
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Publication Detail:
Type:  In Vitro; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  89     ISSN:  8750-7587     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  2000 Dec 
Date Detail:
Created Date:  2000-12-26     Completed Date:  2001-01-11     Revised Date:  2013-09-26    
Medline Journal Info:
Nlm Unique ID:  8502536     Medline TA:  J Appl Physiol (1985)     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  2422-9     Citation Subset:  IM    
Affiliation:
Department Research and Development, Veterans Affairs Medical Center, Pittsburgh, Pennsylvania 15240, USA.
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MeSH Terms
Descriptor/Qualifier:
Acid-Base Equilibrium
Animals
Anoxia / metabolism*
Carbon Dioxide / metabolism*
Intestines / metabolism*
Kinetics
Lactic Acid / metabolism
Models, Biological
Osmolar Concentration
Partial Pressure
Swine
Time Factors
Chemical
Reg. No./Substance:
124-38-9/Carbon Dioxide; 50-21-5/Lactic Acid

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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