Left ventricular function after chronic insulin treatment in diabetic and normal rats

Area of Science:

• Cardiology
• Endocrinology
• Diabetology

Background:

• Streptozotocin-induced diabetes in rats is associated with cardiomyopathy.
• The reversibility of this condition to insulin therapy requires investigation.

Purpose of the Study:

• To determine if insulin therapy can reverse streptozotocin-induced cardiomyopathy.
• To investigate the role of insulin deficiency versus direct cardiotoxicity in this condition.

Main Methods:

• Comparison of heart function in three groups of rats: untreated diabetic, insulin-treated diabetic, and control.
• Isolated working heart perfusion with measurement of cardiac performance indices.
• Assessment of Ca2+-actomyosin ATPase activity and myocardial relaxation times.

Main Results:

• Untreated diabetic rat hearts showed significant functional depressions compared to controls and insulin-treated rats.
• Insulin treatment reversed cardiomyopathy, with some indices suggesting overcorrection.
• Hyperinsulinemia in control rats improved cardiac function, indicating a beneficial effect of insulin.

Conclusions:

• Streptozotocin-induced cardiomyopathy is reversible with insulin therapy.
• The condition results from insulin deficiency, not a direct cardiotoxic effect of streptozotocin.
• Insulin therapy can improve myocardial function in diabetic cardiomyopathy.