Fig. 4.

Metformin ameliorates PM_2.5-induced cardiac dysfunction, myocardial fibrosis and cardiomyocyte apoptosis. After PM_2.5 exposure, the heart weight to body weight ratio (A), LV ejection fraction (B) and mRNA levels of atrial natriuretic peptide (ANP) (C) were measured. Representative heart sections from the control and PM_2.5- or PM_2.5 with metformin-treated WT and AMPKα2^−/− mice were stained with Masson's trichrome (scale bar = 100 μm) and TUNEL assay kit dye (red) plus DAPI (blue) (scale bar = 50 μm) (D). The fibrotic area (E) and the TUNEL-positive cells were quantified (F) were quantified. The mRNA levels of myocardial collagen I and III were measured (G, H). N = 4–7; data are presented as the mean ± SEM; * indicates p < 0.05, ** indicates p < 0.01. (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)