Allodynia, endothelial cell injury and microvascular dysfunction in muscle induced by hind paw IR injury. a, 3 h tourniquet IR (CPIP) (n = 12), but not sham (n = 8) treatment, induces a significant reduction in paw-withdrawal threshold (PWT, g) for 4 weeks post-reperfusion (*P < 0.05 compared to baseline (Bas) or sham). b, 3 h clamping of the blood vessels supplying the hind paw (clamp), but not for 5 min (sham), also induces a significant reduction in PWT (g) 2 and 7 days post-reperfusion compared to rats that were only anesthetized (controls) (all groups n = 8) (*P < 0.05, compared to control). c, There are significantly greater dose-dependent norepinephrine (NE)-induced reductions from baseline in blood flow (peak % decrease in flux) in CPIP (n = 8), as compared to sham (n = 13) rats at 2 days post-reperfusion (*P < 0.05) (data from ). d, e, Electron micrographs of hind paw digital muscle (HPDM) capillaries from a sham-treated (d) and 7 day CPIP (e) rat (muscle fiber (F), endothelial cell nucleus (N), pericyte (P), lumen (*)). f, Capillary walls are thicker (μm) in CPIP (n = 370 from 4 rats), as compared to sham-treated (n = 206 from 4 rats) rats (*P < 0.05). g, h, Low and higher power (inset) photomicrographs of the India Ink-stained blood vessels in HPDM of the contralateral (g) and ipsilateral (h) CPIP hind paw. i, Number of patent vessels stained with India Ink are significantly reduced in the ipsilateral (ipsi) (n = 6–7), compared to contralateral (contra) CPIP (n = 6–7) and sham (n = 6) HPDM between 2 h and 7 days post-reperfusion (*P < 0.05). All data expressed as mean ± s.e.m.