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Predicate | Object |
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rdf:type | |
lifeskim:mentions | |
pubmed:issue |
6
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pubmed:dateCreated |
1995-4-21
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pubmed:abstractText |
Assessing the role of O2 supply in the regulation of cardiac function in O2-limited hearts is crucial to understanding myocardial ischemic preconditioning and adaptation to hypoxia. We exposed isolated Langendorff-perfused rat hearts to either ischemia (low coronary flow) or hypoxemia (low PO2 in the perfusing medium) with matched O2 supply (10% of baseline). Myocardial contractile work and ATP turnover were greater in hypoxemic than in ischemic hearts (P < 0.05; n = 12). Thus, the energy demand was higher during hypoxemia than during ischemia, suggesting that ischemic hearts are more downregulated than hypoxemic hearts. Venous PO2 was 12 +/- 2 and 120 +/- 15 Torr (P < 0.0001) for ischemic and hypoxemic hearts, respectively, but O2 uptake was the same. Lactate release was higher during hypoxemia than during ischemia (9.7 +/- 0.9 vs. 1.4 +/- 0.2 mumol/min, respectively; P < 0.0001). Electrical stimulation (300 min-1; to increase energy demand) increased performance in ischemic (P < 0.005) but not in hypoxemic hearts without changes in venous PO2 or O2 uptake. However, venous lactate concentration and lactate release increased in ischemic (P < 0.002) but not in hypoxemic hearts, suggesting that anaerobic glycolysis provides the energy necessary to meet the increased energy demand in ischemic hearts only. We conclude that high intracellular lactate or H+ concentration during ischemia plays a major role as a downregulating factor. Downregulation disappears in hypoxemic hearts secondary to enhanced washout of lactate or H+.
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pubmed:language |
eng
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pubmed:journal | |
pubmed:citationSubset |
IM
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pubmed:chemical | |
pubmed:status |
MEDLINE
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pubmed:month |
Dec
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pubmed:issn |
8750-7587
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pubmed:author | |
pubmed:issnType |
Print
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pubmed:volume |
77
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
2530-6
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pubmed:dateRevised |
2006-11-15
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pubmed:meshHeading |
pubmed-meshheading:7896587-Animals,
pubmed-meshheading:7896587-Arteries,
pubmed-meshheading:7896587-Cardiac Pacing, Artificial,
pubmed-meshheading:7896587-Coronary Circulation,
pubmed-meshheading:7896587-Diastole,
pubmed-meshheading:7896587-Energy Metabolism,
pubmed-meshheading:7896587-Heart Rate,
pubmed-meshheading:7896587-Male,
pubmed-meshheading:7896587-Myocardial Ischemia,
pubmed-meshheading:7896587-Myocardium,
pubmed-meshheading:7896587-Oxygen,
pubmed-meshheading:7896587-Pressure,
pubmed-meshheading:7896587-Rats,
pubmed-meshheading:7896587-Rats, Sprague-Dawley,
pubmed-meshheading:7896587-Ventricular Function, Left
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pubmed:year |
1994
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pubmed:articleTitle |
Regulation of bioenergetics in O2-limited isolated rat hearts.
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pubmed:affiliation |
Department of Biomedical Science and Technology, Scientific Institute San Raffaele, University of Milan, San Donato Hospital, Italy.
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pubmed:publicationType |
Journal Article,
In Vitro,
Research Support, Non-U.S. Gov't
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