Fig. 2: Sedentary mice have lower capillary density, lower pericyte density, more constricted capillaries and a reduction in baseline saturated oxygen levels over time.

a Example of z-projected images of FITC-gelatine perfused vessels (green) and NG2-DsRed pericytes (red) in the visual cortex (image from E3EX mouse). Scale bar: 80 µm. Projected depth: 100 µm. b Exercise increased capillary density in V1 (for vessels <7 µm in diameter). Dots are average density per brain slice, statistical analysis was conducted on mean values per slice (N = 7–10 sections from N = 3–4 mice). c Pericyte density trends towards being higher in active mice. Statistical analysis was conducted on mean values per slice (N = 5–19 sections from N = 2–4 mice). d Example image of capillary showing pericyte (left, top: green: FITC gelatine, red: DsRed positive pericyte soma); and processed image showing skeleton (blue) and distance map coding distance of each pixel from the parenchyma (centre of vessel is darkest grey). Location of diameter measurements at varying distances from the pericyte soma are marked with red dots. e Capillary diameter as a function of distance from pericyte soma (soma is at 0 μm). f Capillary diameter at the pericyte soma is reduced in sedentary mice (N = 154–1189 pericytes from N = 2–4 mice). g Capillary diameter across the whole vascular network. Sedentary mice trend towards a smaller average diameter than active mice. (N = 5–19 images from N = 2–5 mice). Genotype, exercise and experiment duration did not affect net flux (h), HbT (i) or CMRO2 (j) at baseline. k sO2 was significantly reduced with age but was higher in mice that exercised. Dots show average per animal (N mice: 6–19). Bars and error bars: mean +/- SEM. For details of N and statistical outputs see Supplementary Table 2 in Supplementary Data.