title: A micro-delivery approach for studying microvascular responses to localized oxygen delivery.
abstract: BACKGROUND
  In vivo video microscopy has been used to study blood flow regulation as a function of varying oxygen concentration in microcirculatory networks. However, previous studies have measured the collective response of stimulating large areas of the microvascular network at the tissue surface.
  
  
  OBJECTIVE
  We aimed to limit the area being stimulated by controlling oxygen availability to highly localized regions of the microvascular bed within intact muscle.
  
  
  METHODS
  Gas of varying O(2) levels was delivered to specific locations on the surface of the Extensor Digitorum Longus muscle of rat through a set of micro-outlets (100 μm diameter) patterned in ultrathin glass using state-of-the-art microfabrication techniques. O(2) levels were oscillated and digitized video sequences were processed for changes in capillary hemodynamics and erythrocyte O(2) saturation.
  
  
  CONCLUSIONS
  Oxygen saturations in capillaries positioned directly above the micro-outlets were closely associated with the controlled local O(2) oscillations. Radial diffusion from the micro-outlet is limited to ~75 μm from the center as predicted by computational modeling and as measured in vivo. These results delineate a key step in the design of a novel micro-delivery device for controlled oxygen delivery to the microvasculature to understand the fundamental mechanisms of microvascular regulation of O(2) supply.
authors.affiliation: Biomedical Engineering Graduate Program, The University of Western Ontario, London, ON, Canada.
authors.forename: Nour W
authors.initials: NW
authors.lastname: Ghonaim
authors.forename: Leo W M
authors.initials: LW
authors.lastname: Lau
authors.forename: Daniel
authors.initials: D
authors.lastname: Goldman
authors.forename: Christopher G
authors.initials: CG
authors.lastname: Ellis
authors.forename: Jun
authors.initials: J
authors.lastname: Yang
mesh_terms: D000818:Animals; D001692:Biological Transport / Q000502:physiology; D001783:Blood Flow Velocity / Q000502:physiology; D002196:Capillaries / Q000502:physiology*; D008297:Male; D008833:Microcirculation / Q000502:physiology*; D018715:Microscopy, Video; D010100:Oxygen / Q000378:metabolism*; D010101:Oxygen Consumption / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D010100:Oxygen