Ischemic Preconditioning and Postconditioning Protect the Heart by Preserving the Mitochondrial Network

Area of Science:

• Cardiovascular Science
• Mitochondrial Biology
• Cellular Physiology

Background:

• Mitochondrial fusion forms networks that enhance tolerance to stress and injury.
• Ischemic preconditioning (IPC) and postconditioning (IPost) are established cardioprotective strategies.
• The impact of IPC and IPost on mitochondrial morphology remains largely unknown.

Purpose of the Study:

• To investigate if IPC and IPost modulate mitochondrial morphology.
• To determine if preserved mitochondrial networks contribute to the cardioprotective effects of IPC and IPost.

Main Methods:

• IPC and IPost were applied to H9c2 rat myoblast cells, primary murine cardiomyocytes, and Langendorff-perfused rat hearts.
• Cardiac cell death, mitochondrial morphology, and gene expression of mitochondrial-shaping proteins were assessed after ischemia-reperfusion injury (IRI).

Main Results:

• IPC and IPost significantly reduced cardiac cell death and myocardial infarct size.
• These interventions maintained the mitochondrial network and increased the length of interfibrillar mitochondria.
• Gene expression analysis revealed IPC upregulated Mfn1, while IPost downregulated Drp1 in H9c2 cells and cardiomyocytes. Both IPC and IPost downregulated Drp1 in the perfused heart.

Conclusions:

• IPC and IPost promote mitochondrial fusion and inhibit fission, maintaining the mitochondrial network.
• This preservation of mitochondrial integrity confers cardioprotection against ischemia-reperfusion injury.