The pathomorphological alterations of endocardial endothelium in experimental diabetes and diabetes associated with hyperlipidemia.

The structural alterations of endocardial endothelial cells of the heart right atrium and left ventricle were investigated in Golden Syrian hamsters subjected to streptozotocin-induced diabetes and to a combination of diabetes and diet-induced hyperlipidemia. Animals were examined at time intervals ranging from 2 weeks to 6 months. Anionic sites of the endothelial plasmalemma were visualized by in situ perfusion of cationized ferritin. The results indicated that: (a) both atrial and ventricular endocardial endothelium are affected in streptozotocin-induced diabetes: endothelium converts from continuous into a fenestrated type, (b) although the anionic charge of the plasmalemma decreased in advanced diabetes, the newly formed fenestrae highly bound cationized ferritin, (c) combined diabetes and hyperlipidemia induced more severe alterations of endocardial endothelium: new permeable endothelial structures were formed (transendothelial channels, open intercellular junctions, fused plasmalemmal vesicles), and the cells became particularly enriched in cytoskeleton (intermediate filaments and microtubules), (d) the thick subendocardial layer of connective tissue contained, in the combined experimental model, macrophage derived foam cells indicative for the occurrence of alterations of atherosclerotic type.