title: Short-term unilateral leg immobilization alters peripheral but not central arterial structure and function in healthy young humans.
abstract: Short-term leg immobilization is an acute model of inactivity, which induces vascular deconditioning. The present study was conducted to determine if short-term leg immobilization induced alterations in central and peripheral conduit artery structure (diameter and compliance), function (resting blood flow and mean wall shear rate), and peripheral flow-mediated dilation. Healthy participants (n = 7 women and n = 8 men) were studied before and after 12 days of unilateral leg immobilization. Carotid artery structure and function were unaltered with immobilization indicating that the unilateral immobilization did not have a detectable effect on this representative central artery. In contrast, peripheral measures of arterial structure at the common femoral and popliteal arteries showed significant reductions in both the immobilized and non-immobilized limbs but to a greater extent in the immobilized limbs. Specifically, femoral and popliteal artery compliance and femoral artery diameter were reduced in both the immobilized and the non-immobilized limb (p < 0.05) while popliteal artery diameter was reduced only in the immobilized leg. Popliteal artery flow-mediated dilation, an indicator of peripheral artery function, was increased in the immobilized limb, which parallels reports in paralyzed limbs of spinal-cord-injured individuals. The time course of vascular alterations with inactivity likely follows a sequence of adaptations in arterial structure and function reflecting differing initial flow patterns, and arterial wall composition, and diverse hemodynamic stimuli within different blood vessels.
authors.affiliation: Department of Kinesiology, McMaster University, Hamilton, ON, Canada. m.e.rakobowchuk@leeds.ac.uk
authors.forename: Mark
authors.initials: M
authors.lastname: Rakobowchuk
authors.forename: Jennifer
authors.initials: J
authors.lastname: Crozier
authors.forename: Elisa I
authors.initials: EI
authors.lastname: Glover
authors.forename: Nobuo
authors.initials: N
authors.lastname: Yasuda
authors.forename: Stuart M
authors.initials: SM
authors.lastname: Phillips
authors.forename: Mark A
authors.initials: MA
authors.lastname: Tarnopolsky
authors.forename: Maureen J
authors.initials: MJ
authors.lastname: MacDonald
mesh_terms: D000328:Adult; D001783:Blood Flow Velocity / Q000502:physiology; D001794:Blood Pressure / Q000502:physiology; D005260:Female; D005263:Femoral Artery / Q000033:anatomy & histology* / Q000502:physiology*; D006339:Heart Rate / Q000502:physiology; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D007103:Immobilization / Q000502:physiology*; D007866:Leg / Q000098:blood supply / Q000502:physiology*; D008297:Male; D009929:Organ Size; D011150:Popliteal Artery / Q000033:anatomy & histology* / Q000502:physiology*; D012039:Regional Blood Flow / Q000502:physiology; D012146:Rest / Q000502:physiology; D013997:Time Factors; D014655:Vascular Resistance / Q000502:physiology; D055815:Young Adult