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<record><TEI><teiHeader><fileDesc><titleStmt><title xml:lang="en">Ischemic preconditioning stimulates sodium and proton transport in isolated rat hearts.</title><author><name sortKey="Ramasamy, R" sort="Ramasamy, R" uniqKey="Ramasamy R" first="R" last="Ramasamy">R. Ramasamy</name></author><author><name sortKey="Liu, H" sort="Liu, H" uniqKey="Liu H" first="H" last="Liu">H. Liu</name></author><author><name sortKey="Anderson, S" sort="Anderson, S" uniqKey="Anderson S" first="S" last="Anderson">S. Anderson</name></author><author><name sortKey="Lundmark, J" sort="Lundmark, J" uniqKey="Lundmark J" first="J" last="Lundmark">J. Lundmark</name></author><author><name sortKey="Schaefer, S" sort="Schaefer, S" uniqKey="Schaefer S" first="S" last="Schaefer">S. Schaefer</name></author></titleStmt><publicationStmt><idno type="wicri:source">PMC</idno><idno type="pmid">7657818</idno><idno type="pmc">185770</idno><idno type="url">http://www.ncbi.nlm.nih.gov/pmc/articles/PMC185770</idno><idno type="RBID">PMC:185770</idno><date when="1995">1995</date><idno type="wicri:Area/Pmc/Corpus">000165</idno><idno type="wicri:explorRef" wicri:stream="Pmc" wicri:step="Corpus" wicri:corpus="PMC">000165</idno></publicationStmt><sourceDesc><biblStruct><analytic><title xml:lang="en" level="a" type="main">Ischemic preconditioning stimulates sodium and proton transport in isolated rat hearts.</title><author><name sortKey="Ramasamy, R" sort="Ramasamy, R" uniqKey="Ramasamy R" first="R" last="Ramasamy">R. Ramasamy</name></author><author><name sortKey="Liu, H" sort="Liu, H" uniqKey="Liu H" first="H" last="Liu">H. Liu</name></author><author><name sortKey="Anderson, S" sort="Anderson, S" uniqKey="Anderson S" first="S" last="Anderson">S. Anderson</name></author><author><name sortKey="Lundmark, J" sort="Lundmark, J" uniqKey="Lundmark J" first="J" last="Lundmark">J. Lundmark</name></author><author><name sortKey="Schaefer, S" sort="Schaefer, S" uniqKey="Schaefer S" first="S" last="Schaefer">S. Schaefer</name></author></analytic><series><title level="j">Journal of Clinical Investigation</title><idno type="ISSN">0021-9738</idno><imprint><date when="1995">1995</date></imprint></series></biblStruct></sourceDesc></fileDesc><profileDesc><textClass></textClass></profileDesc></teiHeader><front><div type="abstract" xml:lang="en"><p>One or more brief periods of ischemia, termed preconditioning, dramatically limits infarct size and reduces intracellular acidosis during subsequent ischemia, potentially via enhanced sarcolemmal proton efflux mechanisms. To test the hypothesis that preconditioning increases the functional activity of sodium-dependent proton efflux pathways, isolated rat hearts were subjected to 30 min of global ischemia with or without preconditioning. Intracellular sodium (Nai) was assessed using 23Na magnetic resonance spectroscopy, and the activity of the Na-H exchanger and Na-K-2Cl cotransporter was measured by transiently exposing the hearts to an acid load (NH4Cl washout). Creatine kinase release was reduced by greater than 60% in the preconditioned hearts (P < 0.05) and was associated with improved functional recovery on reperfusion. Preconditioning increased Nai by 6.24 +/- 2.04 U, resulting in a significantly higher level of Nai before ischemia than in the control hearts. Nai increased significantly at the onset of ischemia (8.48 +/- 1.21 vs. 2.57 +/- 0.81 U, preconditioned vs. control hearts; P < 0.01). Preconditioning did not reduce Nai accumulation during ischemia, but the decline in Nai during the first 5 min of reperfusion was significantly greater in the preconditioned than in the control hearts (13.48 +/- 1.73 vs. 2.54 +/- 0.41 U; P < 0.001). Exposure of preconditioned hearts to ethylisopropylamiloride or bumetanide in the last reperfusion period limited in the increase in Nai during ischemia and reduced the beneficial effects of preconditioning. After the NH4Cl prepulse, preconditioned hearts acidified significantly more than control hearts and had significantly more rapid recovery of pH (preconditioned, delta pH = 0.35 +/- 0.04 U over 5 min; control, delta pH = 0.15 +/- 0.02 U over 5 min). This rapid pH recovery was not affected by inhibition of the Na-K-2Cl cotransporter but was abolished by inhibition of the Na-H exchanger. These results demonstrate that preconditioning alters the kinetics of Nai accumulation during global ischemia as well as proton transport after NH4Cl washout. These observations are consistent with stimulation of the Na-K-2Cl cotransporter and Na-H exchanger by preconditioning.</p><sec sec-type="scanned-figures"><title>Images</title><fig id="F1"><graphic xlink:href="jcinvest00015-0296-a" xlink:role="1468"></graphic></fig></sec></div></front></TEI><pmc article-type="research-article"><pmc-comment>The publisher of this article does not allow downloading of the full text in XML form.</pmc-comment>
<front><journal-meta><journal-id journal-id-type="nlm-ta">J Clin Invest</journal-id><journal-title>Journal of Clinical Investigation</journal-title><issn pub-type="ppub">0021-9738</issn></journal-meta><article-meta><article-id pub-id-type="pmid">7657818</article-id><article-id pub-id-type="pmc">185770</article-id><article-categories><subj-group subj-group-type="heading"><subject>Research Article</subject></subj-group></article-categories><title-group><article-title>Ischemic preconditioning stimulates sodium and proton transport in isolated rat hearts.</article-title></title-group><contrib-group><contrib contrib-type="author"><name><surname>Ramasamy</surname><given-names>R</given-names></name></contrib><contrib contrib-type="author"><name><surname>Liu</surname><given-names>H</given-names></name></contrib><contrib contrib-type="author"><name><surname>Anderson</surname><given-names>S</given-names></name></contrib><contrib contrib-type="author"><name><surname>Lundmark</surname><given-names>J</given-names></name></contrib><contrib contrib-type="author"><name><surname>Schaefer</surname><given-names>S</given-names></name></contrib></contrib-group><aff>Department of Internal Medicine, University of California, Davis 95616, USA.</aff><pub-date pub-type="ppub"><month>9</month><year>1995</year></pub-date><volume>96</volume><issue>3</issue><fpage>1464</fpage><lpage>1472</lpage><abstract><p>One or more brief periods of ischemia, termed preconditioning, dramatically limits infarct size and reduces intracellular acidosis during subsequent ischemia, potentially via enhanced sarcolemmal proton efflux mechanisms. To test the hypothesis that preconditioning increases the functional activity of sodium-dependent proton efflux pathways, isolated rat hearts were subjected to 30 min of global ischemia with or without preconditioning. Intracellular sodium (Nai) was assessed using 23Na magnetic resonance spectroscopy, and the activity of the Na-H exchanger and Na-K-2Cl cotransporter was measured by transiently exposing the hearts to an acid load (NH4Cl washout). Creatine kinase release was reduced by greater than 60% in the preconditioned hearts (P < 0.05) and was associated with improved functional recovery on reperfusion. Preconditioning increased Nai by 6.24 +/- 2.04 U, resulting in a significantly higher level of Nai before ischemia than in the control hearts. Nai increased significantly at the onset of ischemia (8.48 +/- 1.21 vs. 2.57 +/- 0.81 U, preconditioned vs. control hearts; P < 0.01). Preconditioning did not reduce Nai accumulation during ischemia, but the decline in Nai during the first 5 min of reperfusion was significantly greater in the preconditioned than in the control hearts (13.48 +/- 1.73 vs. 2.54 +/- 0.41 U; P < 0.001). Exposure of preconditioned hearts to ethylisopropylamiloride or bumetanide in the last reperfusion period limited in the increase in Nai during ischemia and reduced the beneficial effects of preconditioning. After the NH4Cl prepulse, preconditioned hearts acidified significantly more than control hearts and had significantly more rapid recovery of pH (preconditioned, delta pH = 0.35 +/- 0.04 U over 5 min; control, delta pH = 0.15 +/- 0.02 U over 5 min). This rapid pH recovery was not affected by inhibition of the Na-K-2Cl cotransporter but was abolished by inhibition of the Na-H exchanger. These results demonstrate that preconditioning alters the kinetics of Nai accumulation during global ischemia as well as proton transport after NH4Cl washout. These observations are consistent with stimulation of the Na-K-2Cl cotransporter and Na-H exchanger by preconditioning.</p><sec sec-type="scanned-figures"><title>Images</title><fig id="F1"><graphic xlink:href="jcinvest00015-0296-a" xlink:role="1468"></graphic></fig></sec></abstract></article-meta></front></pmc></record>Pour manipuler ce document sous Unix (Dilib)
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