Abnormal function and glucose metabolism in the type-2 diabetic db/db mouse heart

Area of Science:

• Cardiology
• Metabolic Disorders
• Diabetology

Background:

• Type-2 diabetes is associated with cardiovascular complications.
• The db/db mouse is a widely used model for studying type-2 diabetes.
• Cardiac function and metabolism are often altered in diabetic conditions.

Purpose of the Study:

• To investigate cardiac function and glucose metabolism in 6-month-old db/db mice.
• To assess the impact of type-2 diabetes on myocardial glucose uptake during ischemia.
• To evaluate cardiac performance and recovery post-ischemia in this diabetic model.

Main Methods:

• Cine magnetic resonance spectroscopy (MRI) for in vivo cardiac function assessment.
• Langendorff perfusion system to study isolated heart glucose uptake during low-flow ischemia.
• Measurement of cardiac output, heart rate, stroke volume, ejection fraction, and maximum rate of ejection.
• Quantification of total cardiac GLUT4 protein expression.

Main Results:

• Db/db mice showed significantly reduced heart rates, stroke volumes, and cardiac output compared to controls.
• Maximum rate of ejection was significantly lower in db/db mice, despite no difference in ejection fraction.
• Cardiac glucose uptake during ischemia was 21% lower in db/db mouse hearts.
• Post-ischemic recovery of cardiac function was reduced by 30% in db/db mice.
• Total cardiac GLUT4 protein was 56% lower in db/db mice.

Conclusions:

• The db/db mouse model exhibits impaired left ventricular function and reduced cardiac output.
• Diabetic hearts in db/db mice demonstrate impaired insulin-independent glucose uptake during ischemia.
• Reduced glucose uptake contributes to increased myocardial damage and impaired functional recovery after ischemic events in this type-2 diabetes model.