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A Murine Closed-chest Model of Myocardial Ischemia and Reperfusion
Published on: July 17, 2012
Exercise-induced cardioprotection is mediated by a bloodborne, transferable factor
M M Michelsen1, N B Støttrup, M R Schmidt
1Department of Cardiology, Aarhus University Hospital, Denmark. marie.m.michelsen@gmail.com
Basic Research in Cardiology
|March 20, 2012
Summary
High-intensity exercise and remote ischemic preconditioning (rIPC) protect the heart by releasing protective factors into the blood. These factors activate opioid receptors, reducing heart injury after ischemia-reperfusion.
Area of Science:
- Cardiovascular Physiology
- Exercise Physiology
- Pharmacology
Background:
- Myocardial ischemia-reperfusion (I-R) injury poses a significant clinical challenge.
- Exercise is known to offer cardioprotection, but the underlying mechanisms are not fully understood.
- Previous studies suggest humoral factors mediate protection from remote ischemic preconditioning (rIPC).
Purpose of the Study:
- To investigate whether physical exercise preconditioning confers cardioprotection via a humorally mediated pathway.
- To determine if this humorally mediated cardioprotection involves opioid receptor activation.
- To compare the effects of exercise preconditioning with rIPC on myocardial I-R injury.
Main Methods:
- Plasma dialysates were collected from human volunteers before and after high-intensity exercise or rIPC.
- Isolated rabbit hearts were perfused with these dialysates.
- Hearts underwent regional ischemia and reperfusion, with or without naloxone (an opioid receptor antagonist).
- Infarct size and left ventricular developed pressure were assessed.
Main Results:
- Both exercise and rIPC significantly reduced infarct size in rabbit hearts compared to controls.
- Post-ischemic cardiac function (left ventricular developed pressure) showed improvement with exercise and rIPC.
- The cardioprotective effects of both interventions were abolished by co-administration of naloxone.
- This indicates the involvement of opioid receptors in mediating the observed protection.
Conclusions:
- High-intensity exercise preconditioning elicits cardioprotection through a humorally mediated mechanism.
- This protective effect is dependent on opioid receptor activation, similar to rIPC.
- These findings elucidate a key molecular pathway for exercise-induced cardioprotection.
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