Endothelial NOS activity and myocardial oxygen metabolism define the salvageable ischemic time window for ischemic postconditioning
Title
Endothelial NOS activity and myocardial oxygen metabolism define the salvageable ischemic time window for ischemic postconditioning
Creator
Cai M; Li Y J; Xu Y; Swartz H M; Chen C L; Chen Y R; He G L
Publisher
American Journal of Physiology-Heart and Circulatory Physiology
Date
2011
2011-03
Description
Cai M, Li Y, Xu Y, Swartz HM, Chen C, Chen Y, He G. Endothelial NOS activity and myocardial oxygen metabolism define the salvageable ischemic time window for ischemic postconditioning. Am J Physiol Heart Circ Physiol 300: H1069-H1077, 2011. First published January 7, 2011; doi: 10.1152/ajpheart.00694.2010.-Ischemic postconditioning (IPOC) could be ineffective or even detrimental if the index ischemic duration is either too short or too long. The present study is to demonstrate that oxygen supply and metabolism defines a salvageable ischemic time window of IPOC in mice. C57BL/6 mice underwent coronary artery occlusion followed by reperfusion (I/R), with or without IPOC by three cycles of 10 s/10 s R/I. In vivo myocardial tissue oxygenation was monitored with electron paramagnetic resonance oximetry. Regional blood flow (RBF) was measured with a laser Doppler monitor. At the end of 60 min reperfusion, tissue from the risk area was collected, and mitochondrial enzyme activities were assayed. Tissue oximetry demonstrated that I/R induced a reperfusion hyperoxygenation state in the 30- and 45-min but not 15- and 60-min ischemia groups. IPOC attenuated the hyperoxygenation with 45 but not 30 min ischemia. RBF, eNOS phosphorylation, and mitochondrial enzyme activities were suppressed after I/R with different ischemic time, and IPOC afforded protection with 30 and 45 but not 60 min ischemia. Infarct size measurement indicated that IPOC reduced infarction with 30 and 45 min but not 60 min ischemia. Clearly, IPOC protected mouse heart with a defined ischemic time window between 30 and 45 min. This salvageable time window was accompanied by the improvement of RBF due to increased phosphorylated eNOS and the preservation of mitochondrial oxygen consumption due to conserved mitochondrial enzyme activities. Interestingly, this salvageable ischemic time window was mirrored by tissue hyperoxygenation status in the postischemic heart.
Subject
cardioprotection; mice; inhibition; Physiology; Cardiovascular System & Cardiology; activation; dysfunction; reperfusion injury; tissue oxygenation; consumption; blood flow; electron paramagnetic resonance; infarct size; ischemia and reperfusion; mitochondrial enzyme activity; mitochondrial permeability transition; rabbit hearts; regional
Identifier
Format
Journal Article or Conference Abstract Publication
URL Address
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Rights
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Pages
H1069-H1077
Issue
3
Volume
300
Citation
Cai M; Li Y J; Xu Y; Swartz H M; Chen C L; Chen Y R; He G L, “Endothelial NOS activity and myocardial oxygen metabolism define the salvageable ischemic time window for ischemic postconditioning,” NEOMED Bibliography Database, accessed April 25, 2025, https://neomed.omeka.net/items/show/8782.