2.3. Histology

After LPS stimulation for 24 hours, mice were euthanized, and then the heart was harvested for histological analysis with paraffin imbedded sections. The 5 µm thick sections were used for morphological analysis. Histologically, hematoxylin‐eosin (H&E) staining was performed to evaluate the cardiomyocytes arrangement. For immunohistochemistry, the paraffin sections were heated in a pressure cooker for antigen retrieval and incubated with CD68 antibody (ab125212, Abcam) or TUNEL probe. Goat anti‐rabbit EnVisionTM+/horseradish peroxidase reagent was added, followed by subsequent staining with DAB detection kit (Gene Tech, Shanghai, China). For immunofluorescence assay, the sections were incubated with primary antibodies diluted in phosphate buffered saline (PBS), supplemented with 1% BSA and 1% Triton X‐100 overnight at 4°C. The following primary antibodies were used: Serca (Abcam, ab2816) and RyR2 (Abcam, ab2868). The primary antibodies were detected with Alexa Fluor 488 goat anti‐mouse/rabbit IgG and Alexa Fluor 568 goat anti‐mouse/rabbit IgG and incubated at 37°C for 60 minutes. Quantification was performed with Image‐Pro Plus 6.0 software (Media Cybernetics, Bethesda, MD).