Ischemic preconditioning depends on interaction between mitochondrial KATP channels and actin cytoskeleton

Area of Science:

• Cardiovascular Physiology
• Cellular Biology
• Biochemistry

Background:

• Ischemic preconditioning (PC) protects the heart from injury, but its precise molecular mechanisms remain debated.
• Mitochondrial ATP-sensitive K+ (KATP) channels and the actin cytoskeleton are proposed key effectors in PC.

Purpose of the Study:

• To investigate the roles of mitochondrial KATP channels and the actin cytoskeleton in mediating protection during ischemic preconditioning.

Main Methods:

• Rabbits underwent regional ischemia and reperfusion, with PC induced by brief ischemia/reperfusion.
• Mitochondrial KATP channel opener (diazoxide) and p38/JNK activator (anisomycin) effects were tested.
• Isolated cardiomyocytes were subjected to simulated ischemia, with PC, diazoxide, pinacidil, anisomycin, and cytochalasin D evaluated for protection against osmotic fragility.

Main Results:

• PC significantly reduced infarct size in rabbits.
• Diazoxide mimicked PC protection, which was blocked by 5-hydroxydecanoate (5-HD), a mitochondrial KATP channel inhibitor.
• In cardiomyocytes, PC, diazoxide, and pinacidil reduced osmotic fragility, an effect abolished by 5-HD or cytochalasin D (cytoskeleton disruptor).

Conclusions:

• Mitochondrial KATP channels are crucial for PC-induced cardioprotection.
• The actin cytoskeleton is also essential for PC and related pharmacological protection.
• Both mitochondrial KATP channels and cytoskeletal integrity are vital end-effectors in ischemic preconditioning.