Akt activation preserves cardiac function and prevents injury after transient cardiac ischemia in vivo

Area of Science:

• Cardiovascular Biology
• Molecular Cardiology
• Biomedical Research

Background:

• Serine-threonine kinase Akt is activated by cardioprotective ligand-receptor systems.
• Akt activation reduces cardiomyocyte apoptosis during transient ischemia.
• The precise role of Akt in cardiac dysfunction and infarction is not fully understood.

Purpose of the Study:

• To investigate the cardioprotective effects of constitutively active Akt (myr-Akt) in a rat model of cardiac ischemia-reperfusion injury.
• To elucidate the mechanisms underlying Akt-mediated protection, including effects on cardiomyocyte apoptosis, cardiac function, and glucose metabolism.

Main Methods:

• In vivo gene transfer of myr-Akt in a rat model of ischemia-reperfusion.
• Assessment of infarct size and cardiomyocyte apoptosis.
• Measurement of cardiac function, including regional wall thickening and pressure changes (+dP/dt, -dP/dt).
• In vitro studies on hypoxic cardiomyocytes to evaluate calcium transients and shortening.
• Analysis of sarcolemmal glucose transporter 4 (Glut-4) expression and glucose uptake.

Main Results:

• myr-Akt gene transfer reduced infarct size by 64% and cardiomyocyte apoptosis by 84%.
• Akt activation restored cardiac function, including regional wall thickening and pressure dynamics (+dP/dt, -dP/dt).
• myr-Akt prevented hypoxia-induced abnormalities in cardiomyocyte calcium handling and contraction.
• Akt enhanced Glut-4 expression and glucose uptake, comparable to insulin treatment.

Conclusions:

• Akt activation provides significant cardioprotection against transient ischemia.
• This protection is attributed to both inhibition of cardiomyocyte death and improvement of surviving cardiomyocyte function.
• Akt represents a key therapeutic target for ischemic heart disease and potentially other cardiac conditions.