Preserved flow-mediated dilation in the inactive legs of spinal cord-injured individuals

Abstract

The aim of the study was to assess endothelial function, measured by flow-mediated dilation (FMD), in an inactive extremity (leg) and chronically active extremity (arm) within one subject. Eleven male spinal cord-injured (SCI) individuals and eleven male controls (C) were included. Echo Doppler measurements were performed to measure FMD responses after 10 and 5 min of arterial occlusion of the leg (superficial femoral artery, SFA) and the arm (brachial artery, BA), respectively. A nitroglycerine spray was administered to determine the endothelium independent vasodilatation in the SFA. In the SFA, relative changes in FMD were significantly enhanced in SCI compared with C (SCI: 14.1 ± 1.3%; C: 9.2 ± 2.3%), whereas no differences were found in the BA (SCI: 12.5 ± 2.9%; C: 14.2 ± 3.3%). Because the FMD response is directly proportional to the magnitude of the stimulus, the FMD response was also expressed relative to the shear rate. No differences between the groups were found for the FMD-to-shear rate ratio in the SFA (SCI:0.061 ± 0.023%/s⁻¹; C: 0.049 ± 0.024%/s⁻¹), whereas the FMD-to-shear rate ratio was significantly decreased in the BA of SCI individuals (SCI: 0.037 ± 0.01%/s⁻¹; C: 0.061 ± 0.027%/s⁻¹). The relative dilatory response to nitroglycerine did not differ between the groups. (SCI: 15.6 ± 2.0%; C: 13.4 ± 2.3%). In conclusion, our results indicate that SCI individuals have a preserved endothelial function in the inactive legs and possibly an attenuated endothelial function in the active arms compared with controls.