title: NADH videofluorimetry to monitor the energy state of skeletal muscle in vivo.
abstract: BACKGROUND
  Reduction of the cellular energy state during ischemia of the limbs is an important determinant for development of necrosis. Since energy conversion in the mitochondria is based on electron transport from NADH to molecular O2, the NADH/NAD+ redox couple reflects the mitochondrial redox state and cellular O2 requirement. The applicability of NADH videofluorimetry to monitor noninvasively changes in the energy state of intact resting skeletal muscle as a function of oxygenation was investigated in a rat model.
  
  
  METHODS
  In mechanically ventilated rats (n = 6), NADH fluorescence images of the gracilis muscle were recorded under different oxygenation conditions. Induction of anoxic and ischemic hypoxia were verified by simultaneous measurement of tissue oxygen pressure and afferent blood flow.
  
  
  RESULTS
  Anoxic hypoxia and ischemic hypoxia increased the NADH fluorescence intensity by 46.0 +/- 15.0 and 30.8 +/- 26.4%, respectively. The response time of NADH fluorescence intensity, tissue oxygen pressure, and afferent blood flow was similar during development of anoxic and ischemic hypoxia. Upon reperfusion and reoxygenation, however, NADH fluorescence intensity changed significantly earlier than tissue oxygen pressure as measured by an oxygen needle electrode.
  
  
  CONCLUSIONS
  These results demonstrate that changes in NADH fluorescence intensity reflect oxygenation changes in intact skeletal muscle in vivo. Since NADH videofluorimetry, in contrast to oxygen needle electrode measurements, noninvasively visualizes temporal and regional changes in the energy state of skeletal muscle, this technique has the potential to improve clinical evaluation of ischemia/reperfusion injury and tissue viability.
authors.affiliation: Department of Surgery, University Hospital Rotterdam, The Netherlands.
authors.forename: L
authors.initials: L
authors.lastname: van der Laan
authors.forename: A
authors.initials: A
authors.lastname: Coremans
authors.forename: C
authors.initials: C
authors.lastname: Ince
authors.forename: H A
authors.initials: HA
authors.lastname: Bruining
mesh_terms: D000818:Animals; D015687:Cell Hypoxia / Q000502:physiology; D004734:Energy Metabolism; D000860:Hypoxia / Q000378:metabolism; D007511:Ischemia / Q000378:metabolism; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism*; D009243:NAD / Q000378:metabolism*; D010100:Oxygen / Q000097:blood; D051381:Rats; D017208:Rats, Wistar; D013050:Spectrometry, Fluorescence; D014741:Video Recording
chemical_list: D009243:NAD; D010100:Oxygen