Exogenous 10 kDa-Heat Shock Protein Preserves Mitochondrial Function After Hypoxia/Reoxygenation

Area of Science:

• Cardiovascular Science
• Mitochondrial Biology
• Cellular Physiology

Background:

• Ischemic preconditioning (IPC) confers myocardial protection against ischemia/reperfusion (I/R) injury through humoral factors.
• 10 kDa-heat shock protein (HSP10) and 5-10 kDa small peptides (5-10-sP) have been identified as cardioprotective agents released during IPC.

Purpose of the Study:

• To investigate the direct impact of exogenous HSP10 and 5-10-sP on mitochondrial function following I/R injury.
• To elucidate the specific signaling pathways, including protein kinase C (PKC) and mitochondrial ATP-sensitive potassium channels (mKATP), involved in the protective effects.

Main Methods:

• Isolated rat hearts were subjected to global ischemia and reperfusion (I/R) with or without pre-treatment with 5-10-sP or HSP10.
• Mitochondrial function, including ADP-stimulated respiration, ATP production, and reactive oxygen species (ROS) formation, was assessed post-I/R.
• Experiments involved pharmacological inhibition of PKC and mKATP channels, as well as direct incubation of isolated mitochondria with HSP10/5-10-sP under hypoxic/reoxygenation conditions.

Main Results:

• Infusion of 5-10-sP and HSP10 significantly improved mitochondrial respiration and ATP production while reducing ROS formation compared to controls.
• The protective effects of 5-10-sP and HSP10 were abolished by PKC and mKATP channel blockers.
• Direct incubation demonstrated that HSP10 protects mitochondria against hypoxia/reoxygenation injury via mKATP activation.

Conclusions:

• Mitochondria are a key target for the cardioprotective effects of 5-10-sP and HSP10.
• The cardioprotection mediated by these factors is dependent on the activation of PKC and mKATP channels.
• HSP10 exerts direct protective effects on mitochondria, particularly through mKATP channel activation, against hypoxia/reoxygenation injury.