title: Short communication: Subcellular motion compensation for minimally invasive microscopy, in vivo: evidence for oxygen gradients in resting muscle.
abstract: BACKGROUND
  In vivo microscopy seeks to observe dynamic subcellular processes in a physiologically relevant context. A primary limitation of optical microscopy in vivo is tissue motion, which prevents physiological time course observations or image averaging.
  
  
  OBJECTIVE
  To develop and demonstrate motion compensation methods that can automatically track image planes within biological tissues, including the tissue displacements associated with large changes in blood flow, and to evaluate the effect of global hypoxia on the regional kinetics and steady state levels of mitochondrial NAD(P)H.
  
  
  RESULTS
  A dynamic optical microscope, with real-time prospective tracking and retrospective image processing, was used collect high-resolution images through cellular responses to various perturbations. The subcellular metabolic response to hypoxia was examined in vivo. Mitochondria closest to the capillaries were significantly more oxidized at rest (67+/-3%) than the intrafibrillar mitochondria (83+/-3%; P<0.0001) in the same cell.
  
  
  CONCLUSIONS
  These data are consistent with the hypothesis that a significant oxygen gradient from capillary to muscle core exists at rest, thereby reducing the oxidative load on the muscle cell.
authors.affiliation: Laboratory of Cardiac Energetics, National Heart, Lung, and Blood Institute,/NIH,10 Center Drive, Bethesda, MD 20892, USA.
authors.forename: James L
authors.initials: JL
authors.lastname: Schroeder
authors.forename: Merav
authors.initials: M
authors.lastname: Luger-Hamer
authors.forename: Randall
authors.initials: R
authors.lastname: Pursley
authors.forename: Tom
authors.initials: T
authors.lastname: Pohida
authors.forename: Chris
authors.initials: C
authors.lastname: Chefd'hotel
authors.forename: Peter
authors.initials: P
authors.lastname: Kellman
authors.forename: Robert S
authors.initials: RS
authors.lastname: Balaban
mesh_terms: D000818:Animals; D016477:Artifacts; D002196:Capillaries / Q000378:metabolism; D000860:Hypoxia / Q000378:metabolism* / Q000503:physiopathology; D007700:Kinetics; D035002:Lower Extremity; D051379:Mice; D036641:Microscopy, Fluorescence, Multiphoton; D008931:Mitochondria, Muscle / Q000378:metabolism*; D009038:Motion; D018482:Muscle, Skeletal / Q000098:blood supply / Q000378:metabolism*; D009249:NADP / Q000378:metabolism*; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D010100:Oxygen / Q000097:blood / Q000378:metabolism*; D025341:Principal Component Analysis; D012039:Regional Blood Flow; D015203:Reproducibility of Results; D012815:Signal Processing, Computer-Assisted
chemical_list: D009249:NADP; D010100:Oxygen