Cardiac ultrastructure in streptozotocin-induced diabetic rats.

ABSTRACT

Objective: To examine the alterations of four cardiac chambers in the streptozotocin (STZ)-induced diabetic rats by using light and transmission electron microscopies Materials and Methods: Eleven STZ-induced diabetic and six control adult male Sprague-Dawley rats were applied. After the induction for 24 weeks, all heart chambers were proceeded with histological and ultrastructural techniques. Results: In the diabetes, swollen endothelial and mesothelial cells laid on thick basal lamina, and their cytoplasm comprised numerous pinocytotic vesicles, vacuoles, and dilated rER. The subendocardial and subepicardial layers were enlarged with accumulations of collagen fibrils. Both cardiac myocytes and Purkinje fibers became hypertrophy. The interstitial fibrosis, contraction band necrosis, and infiltrations of lymphocytes and macrophages were observed in some areas of myocardium. The myocardium of the left ventricle showed interstitial hemorrhage. In both cardiac myocytes and Purkinje fibers, the arrangement of sarcomere was irregular with lost myofilaments. Moreover, swollen mitochondria with disrupted cristae were examined and increased in number. The number of specific atrial granules decreased in the atrial cardiac myocytes. Increased lipid droplets and myelin figures were seen in the myocytes. The intercalated disc was disrupted in some portions. The capillary lumen was narrowed due to swollen endothelial cells with thick basal lamina. Conclusion: DM causes numerous cardiac alterations in all three layers of four chambers. This study provides an important basic knowledge for understanding the pathological changes and options for further therapeutic treatment of cardiac complications in the diabetic patients.