Linked Life Data

8585860

Source:http://linkedlifedata.com/resource/pubmed/id/8585860

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
5
pubmed:dateCreated
1996-3-20
pubmed:abstractText
A study of substrate selection in the isolated heart was made using 13C NMR isotopomer analysis, a method that unequivocally identifies relative substrate utilization. This technique has several advantages over conventional approaches used to study this problem. It detects the labeling of metabolic end-products present in tissue, as opposed to more indirect methods such as measurement of respiratory quotient, arteriovenous differences, or specific activity changes in the added substrate. It also has advantages over methods such as 14CO2 release, which may involve dilution of label with unlabeled pools before CO2 release. Furthermore, it can measure the relative oxidation of up to four substrates in a single experiment, which other labeling techniques cannot conveniently achieve. Substrate selection was considered in light of its effects on myocardial efficiency and recovery from ischemia. A mixture of four substrates (acetoacetate, glucose, lactate, and a mixture of long chain fatty acids), present at physiological concentration (0.17, 5.5, 1.2, and 0.35 mM, respectively), was examined. This is the first use of such a mixture in the study of substrate selection in an isolated organ preparation. At these concentrations, it was found that fatty acids supplied the majority of the acetyl-CoA (49%), and a substantial contribution was also provided by acetoacetate (23%). This suggests that the ketone bodies are a more important substrate than generally considered. Indeed, normalizing the relative utilizations on the basis of acetyl-CoA equivalents, ketone bodies were by far the preferred substrate. The relative lactate oxidation was only 15%, and glucose oxidation could not be detected. No change in utilization was detected after 15 min of ischemia followed by 40 min of reperfusion. The change in substrate selection with afterload was examined, to mimic the stress-related changes in workload found with ischemia. Only minor changes were found. Substrate selection from the same group of substrates, but employing concentrations observed during starvation, was also assessed. This represents the state during which most clinical treatments and evaluations are performed. In this case, acetoacetate was the most used substrate (78%), with small and equal contributions from fatty acids and endogenous substrates; the oxidation of lactate was suppressed.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:issn
0300-8428
pubmed:author
pubmed:issnType
Print
pubmed:volume
90
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
388-96
pubmed:dateRevised
2007-11-15
pubmed:meshHeading
pubmed:articleTitle
Substrate selection in the isolated working rat heart: effects of reperfusion, afterload, and concentration.
pubmed:affiliation
Department of Radiology, UT Southwestern Medical Center, Mary Nell and Ralph B. Rogers Magnetic Resonance Center, Dallas 75235-9085, USA.
pubmed:publicationType
Journal Article, In Vitro, Research Support, U.S. Gov't, P.H.S., Research Support, U.S. Gov't, Non-P.H.S.