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Flow‐mediated dilatation in the superficial femoral artery is nitric oxide mediated in humans
Author(s) -
Kooijman M.,
Thijssen D. H. J.,
De Groot P. C. E.,
Bleeker M. W. P.,
Van Kuppevelt H. J. M.,
Green D. J.,
Rongen G. A.,
Smits P.,
Hopman M. T. E.
Publication year - 2008
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.2007.145722
Subject(s) - medicine , omega n methylarginine , femoral artery , brachial artery , deconditioning , saline , nitric oxide , cuff , anesthesia , endothelium , vasodilation , cardiology , nitric oxide synthase , blood pressure , surgery
Flow‐mediated dilatation (FMD) of the brachial and radial arteries is an important research tool for assessment of endothelial function in vivo , and is nitric oxide (NO) dependent. The leg skeletal muscle vascular bed is an important territory for studies in exercise physiology. However, the role of endothelial NO in the FMD response of lower limb arteries has never been investigated. The purpose of this study was to examine the contribution of NO to FMD in the superficial femoral artery in healthy subjects. Since physical inactivity may affect endothelial function, and therefore NO availability, spinal cord‐injured (SCI) individuals were included as a model of extreme deconditioning. In eight healthy men (34 ± 13 years) and six SCI individuals (37 ± 10 years), the 5 min FMD response in the superficial femoral artery was assessed by echo‐Doppler, both during infusion of saline and during infusion of the NO synthase blocker N G ‐monomethyl‐ l ‐arginine ( l ‐NMMA). In a subset of the controls ( n = 6), the 10 min FMD response was also examined using the same procedure. The 5 min FMD response in controls (4.2 ± 0.3%) was significantly diminished during l ‐NMMA infusion (1.0 ± 0.2%, P < 0.001). In SCI, l ‐NMMA also significantly decreased the FMD response (from 8.2 ± 0.4% during saline to 2.4 ± 0.5% during l ‐NMMA infusion). The hyperaemic flow response during the first 45 s after cuff deflation was lower in both groups during infusion of l ‐NMMA, but the effect of l ‐NMMA on FMD persisted in both groups after correction for the shear stress stimulus. The 10 min FMD was not affected by l ‐NMMA (saline: 5.4 ± 1.6%, l ‐NMMA: 5.6 ± 1.5%). Superficial femoral artery FMD in response to distal arterial occlusion for a period of 5 min is predominantly mediated by NO in healthy men and in the extremely deconditioned legs of SCI individuals.