| Ischemic Postconditioning Inhibits Mitochondrial Permeability Transition Pore via Opioid Receptor Activation in Intact Rat Heart. |
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Yong Cheol Lee, Young Ho Jang, Jin Mo Kim, Ae Ra Kim, Seung Ryong Lee, Yoon Nyun Kim, Ji Hee Hong |
1Department of Anesthesiology and Pain Medicine, School of Medicine, Keimyung University, Daegu, Korea. eonjo@hotmail.com
2Department of Pharmacology, School of Medicine, Keimyung University, Daegu, Korea. |
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| Abstract |
BACKGROUND
Ischemic postconditioning (Post-C), brief cycles of myocardial ischemia and reperfusion during the early phase of reperfusion, is considered as a novel adjunct strategy to protect myocardium.However, the exact mechanism remains unclear and should be determined.
METHODS
The hearts of male Wistar rats were subjected to 30 min ischemia and 2 hrs reperfusion.Control rats had no intervention either before or after left coronary artery occlusion.Post-C was elicited by 6 cycles of 10s reperfusioninterspersed by 10s ischemia immediately after onset of reperfusion.Subsets of postconditioning rats were treated with drugs as followings; naloxone (non-selective opioid receptor antagonist), naltrindole (a delta-opioid receptor antagonist), SB216763 (a glycogen synthase kinase 3beta inhibitor, GSK-3beta inhibitor), or atractyloside (a mitochondrial permeability transition pore opener, mPTP opener).
RESULTS
Post-C significantly reduced infarct size (15.9 +/- 2.4%, P = 0.003) compared to control (29.9 +/- 3.7%).The anti-infarct effect by Post-C was blocked by both naloxone (25.5 +/- 3.9%, P = 0.044) and naltrindole (26.9 +/- 2.3%, P = 0.022).Infarct size limiting effect by Post-C was also abolished by atractyloside (30.6 +/- 3.6%, P = 0.003).In SB216763 with naloxone treated animals, the infarct size was decreased (17.4 +/- 3.2%, P = 0.007) but not in SB216763 with atractyloside treated animals (27.4 +/- 2.6%) compared to control.
CONCLUSIONS
These data suggest that Post-C may protect myocardium by inhibiting mPTP opening via delta-opioid receptor activation.GSK-3beta is a downstream mediator of opioid receptors and an upstream mediator of mPTP opening in Post-C. |
| Key Words:
ischemia; mitochondria; opioid receptor; postconditioning; reperfusion |
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