Fig. 4

Hypertension and tachycardia increase tracer efflux from the grey matter into the white matter. Quantification of ovalbumin (AFO-647) tracer fluorescence within microscopic whole axial sections, grey matter and white matter. a, b After injection of AFO-647 into the spinal grey matter, the fluorescence intensity of redistributed tracer was measured within the grey and white matter of levels remote from the injection site (C2–6 and T2–T4). b The injection was verified using microspheres added to the tracer. c, f, i After injection of tracer there was no significant difference in whole axial section, grey and white matter fluorescence intensities between spontaneous breathing (SB) and mechanically ventilated control (MV) rats. d, g, j There was significantly higher fluorescence in hypertensive (High MAP) rats (compared with Low MAP controls) in the whole cord and white matter. e, h, k There were similar findings in tachycardic (High HR) rats compared with controls (Low HR). On post hoc analysis, the difference in fluorescence intensities reached significance at T2 in the whole spinal cord. Two-way analysis of variance (ANOVA) post hoc Bonferroni’s, *p < 0.05. All error bars are expressed as ± SEM, n = 10 rats