Fig. 2.

Metformin alleviates functional and structural alterations during vascular senescence. PWV measurement represents a valid tool for noninvasively quantifying arterial stiffness. A and B, PWV was higher in Ang II-infused mice in comparison with age-matched control animals, while metformin administration decreased PWV in comparison with the Ang II-infusion group (one-way ANOVA, Tukey post hoc; n = 9). Alterations to collagen and elastin contents as well as aortic wall arrangement were assessed by Masson’s Trichrome, Picrosirius Red, and Van Gieson’s staining of aortic tissue ring samples. C, Morphometric assessment of the four mouse groups after Masson’s trichrome staining. F, G, H, I, and J, Medial layer thicknesses, medial cross-sectional areas, lumen diameters, medial thickness/lumen diameter ratios, and collagen levels were calculated (one-way ANOVA, Tukey post hoc; n = 6–7). Scale bar = 200 μm. D and K, Circularly polarized light detection of collagen fibers, with collagen contents obtained within randomly selected fields. Optical density was determined (one-way ANOVA, Tukey post hoc; n = 3). Scale bar = 200 μm. E, Elastin fibers were detected by Van Gieson’s staining; scale bar = 200 μm. Data are mean ± SD. *P < 0.05, ^**P < 0.01, and ^***P < 0.001 versus control group or for indicated comparisons. PWV, pulse wave velocity.