Hematoxylin and eosin (H&E) staining

Myocardial tissue from the heart apex of rats was fixed in 10% paraformaldehyde for 12 h at room temperature. H&E staining was subsequently performed according to routine procedure. Tissues were sliced into 3–4 µm sections. Following a wash with deionized water for 1–2 min, tissue sections were stained with hematoxylin for 50 sec at room temperature and rinsed with deionized water for 1–2 min. Following a wash in absolute ethanol (containing 1% HCl), sections were subsequently stained with eosin for 6–8 sec at room temperature. A total of 5 different fields of view were analyzed under a light microscope at a magnification of ×200 (Nikon Tis fluorescence microscopy; Nikon Corporation, Tokyo, Japan).