Fig. 4

Pathological hemodynamic changes in dAVs post-SCI. a Representative kymographs of blood flow in dAVs obtained by two-photon microscopy using 150 kDa FITC-dextran pre- and post-SCI from the same vessel. The slope of the streak equals the velocity of each blood cell. Scale bar: vertical = 100 ms, horizontal = 200 μm. b Quantification of blood flow velocity in dAVs on the injured spinal segment within one-hour observation during NT or TTM (n = 8 mice, total 184 venules). The boundaries of the box indicate the 25th and 75th percentiles, and the whiskers indicate the 5th and 95th percentiles, the same below. c Blood flow velocity in each venule was normalized by self-comparison pre-SCI. d Representative maximum projection of the vessels in (a). The average diameter was calculated within the ROI (red frame). Scale bar = 100 μm. e Average diameter of dAVs in the ROI pre- and post-SCI with NT or TTM. f Pressure drop at dAVs in the ROIs pre- and post-SCI. The pressure drop in the ROI was calculated by the simplified Poiseuille formula and Radon-transform algorithm. A higher pressure drop indicated an increased pressure upstream in the ROI to maintain blood flow. g The shear rate and shear force in the dAVs during blood flow acceleration post-SCI were calculated according to the Newton inner friction law. The shear force is a frictional force exerted on the endothelium by blood flow. h The blood flow volume in dAVs within one hour post-SCI. i, j Blood perfusion in the dSV and parenchyma within an hour post-SCI with NT or TTM was measured by noncontact laser Doppler flowmetry. The redshift indicated more red blood cell movement (n = 6 mice). Data are presented as the mean ± SEM; *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001; nested, one-way (b, e–h, j) and two-way (j) ANOVA