Improvement of cardiac performance and metabolism in long-term diabetes mellitus after treatment with insulin [see comment

Rat hearts induced diabetic by administration of streptozotocin were investigated after 8 months using the isolated perfused working rat heart model at a physiological workload of approximately 45 min. They are hemodynamically characterized by a significantly reduced cardiac output (p < 0.001) and metabolically by a 49% reduction in glucose utilization (p < 0.001), mainly caused by reduced glucose uptake (p < 0.001) and an increased lactate and pyruvate production (p < 0.001), associated with a reduction of oxygen consumption by 44% (p < 0.001). Both lead to reduced ATP and CP myocardial tissue levels (p < 0.001). Similar results with respect to cardiac performance and metabolism are observed already after 2 months of diabetes. Treating these rats after 2 months of diabetes with insulin for 6 months, cardiac output (ns), cardiac metabolism (ns), oxygen uptake (ns) as well as ATP and CP levels (ns) are restored, indicating that normalization of cardiac function in this model depends mainly on the restored cardiac metabolism. These findings were associated with changes in the angioarchitecture as demonstrated.