title: Time course of arterial vascular adaptations to inactivity and paralyses in humans.
abstract: OBJECTIVE
  The aim of the present study was to assess the time course of vascular adaptations to inactivity and paralyses in humans. The spinal cord-injured (SCI) population offers a unique "human model of nature" to assess peripheral vascular adaptations and its time course to extreme inactivity and paralyses.
  
  
  METHODS
  Arterial diameters and red blood cell velocity of the carotid artery (CA), common femoral artery (FA), and brachial artery (BA) were measured using echo Doppler ultrasound. Fifteen SCI persons with lesions varying from 6 wk to 13 months postinjury participated in a cross-sectional study (SCI-CS), 6 SCI individuals were included for longitudinal measurements (SCI-L) at weeks 6, 8, 12, 16, 20, and 24 after the trauma, and 16 able-bodied individuals served as a control group (C).
  
  
  RESULTS
  Within 6 wk after the SCI, diameter (SCI-CS: 0.68 +/- 0.09 cm, SCI-L: 0.67 +/- 0.04 cm, C: 0.95 +/- 0.07 cm) and blood flow (SCI-CS: 299 +/- 112 mL x min(-1), SCI-L 279: +/- 52 mL x min(-1), C: 405 +/- 97 mL x min(-1)) of the femoral artery were significantly reduced (P < 0.001), and local femoral wall shear rate was almost doubled in SCI-CS and SC-L compared with C (P < 0.001). No further changes in femoral arterial properties were observed between week 6 and 13 months postinjury in SCI-L as well as SCI-CS. Carotid and brachial artery diameter and flow were similar in SCI and C and did not change between 6 wk and 13 months after the injury.
  
  
  CONCLUSIONS
  We conclude that the process of vascular adaptations to inactivity and paralyses in humans seems to be largely completed within weeks.
authors.affiliation: Department of Physiology, University Medical Centre Nijmegen, The Netherlands. p.degroot@fysiol.umcn.nL
authors.forename: Patricia C E
authors.initials: PC
authors.lastname: De Groot
authors.forename: Dirk H J M
authors.initials: DH
authors.lastname: Van Kuppevelt
authors.forename: Cees
authors.initials: C
authors.lastname: Pons
authors.forename: Govert
authors.initials: G
authors.lastname: Snoek
authors.forename: Luc H V
authors.initials: LH
authors.lastname: Van Der Woude
authors.forename: Maria T E
authors.initials: MT
authors.lastname: Hopman
mesh_terms: D000222:Adaptation, Physiological; D001158:Arteries / Q000000981:diagnostic imaging / Q000502:physiology*; D003430:Cross-Sectional Studies; D004912:Erythrocytes / Q000502:physiology; D005260:Female; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D008297:Male; D010243:Paralysis / Q000503:physiopathology*; D010809:Physical Fitness / Q000502:physiology*; D011446:Prospective Studies; D013119:Spinal Cord Injuries / Q000503:physiopathology; D013997:Time Factors; D014463:Ultrasonography