Fig. 3

Pathological features of diabetic cardiomyopathy. a Cardiac hypertrophy in diabetic rats. Comparison of heart size (A1) (scale bar 2 mm), representative cross sections of hearts at the papillary muscle level (A2) (scale bar 2 mm), and longitudinal sections (A3) and transverse sections (A4) of left ventricle stained with hematoxylin and eosin (H&E; scale bar 50 μm) in rats in the control, diabetes mellitus (DM), and diabetes mellitus + trimetazidine (DM + TMZ) groups (n = 5–6 per group). b Ratio of heart weight to body weight in rats in the control, DM, and DM + TMZ groups. c Cardiac fibrosis in diabetic rats. Interstitial fibrosis as shown by Masson-Trichrome staining [collagen is green and myocardium red; scale bar 50 μm (C1)] and Picrosirius red staining (collagen fibers stained bright red; bright-field (C2) and dark-field (C3); scale bar 100 μm). Perivascular fibrosis as shown by Masson-Trichrome staining (C4) (scale bar 100 μm) and Picrosirius red staining [bright-field (C5) and dark-field (C6); scale bar 100 μm]. d Comparison of collagen volume fraction (CVF) in rats in the control, DM, and DM + TMZ groups. e Comparison of perivascular collagen area/luminal area (PVCA/LA) ratio in rats in the control, DM, and DM + TMZ groups. Values are mean ± SEM. *p < 0.05 compared with control group; and ^# p < 0.05 compared with diabetes group