title: Low flow after global ischemia to improve postischemic myocardial function and bioenergetics.
abstract: OBJECTIVE
  In this study, we test the hypothesis that a period of low flow perfusion before full reperfusion improves ventricular function and bioenergetics.
  
  
  METHODS
  Prospective, randomized, controlled animal study.
  
  
  METHODS
  Research laboratory.
  
  
  METHODS
  Sprague-Dawley rats.
  
  
  METHODS
  Hearts were perfused with Krebs-Henseleit buffer at 85 mm Hg. The protocol consisted of 10 mins of baseline flow, 15 mins of global ischemia, 5 mins of low flow ischemia, and 30 mins of reperfusion. Groups received 10% or 1% of baseline flow during the low flow period. A control group received 0% low flow (20 mins of global ischemia).
  
  
  RESULTS
  Left ventricular function was continuously measured. Hearts were freeze-clamped at various time points, and metabolites were measured. At 10% flow, following global ischemia, both left ventricular function and bioenergetics improved compared with 0% flow and 1% flow. At 1% flow, no changes in function were seen and adenosine 5'-triphosphate concentrations decreased during reperfusion, compared with no flow (9.4 +/- 1.0 vs. 13.2 +/- 1.0 micromol/g of dry weight, p <.01).
  
  
  CONCLUSIONS
  Following global ischemia but before full reperfusion, a period of low flow improves postischemic myocardial function and energetic recovery, only if a certain level of low flow is met. Very low flow may further reduce bioenergetic recovery without improvement in postischemic function, compared with continuous global ischemia.
authors.affiliation: Department of Emergency Medicine, The Ohio State University, Columbus, OH 43210, USA.
authors.forename: Paul F
authors.initials: PF
authors.lastname: Klawitter
authors.forename: Holt N
authors.initials: HN
authors.lastname: Murray
authors.forename: Thomas L
authors.initials: TL
authors.lastname: Clanton
authors.forename: Brian S
authors.initials: BS
authors.lastname: Palmer
authors.forename: Mark G
authors.initials: MG
authors.lastname: Angelos
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D016887:Cardiopulmonary Resuscitation; D004734:Energy Metabolism; D006323:Heart Arrest / Q000503:physiopathology / Q000628:therapy*; D008297:Male; D015425:Myocardial Reperfusion / Q000379:methods*; D017682:Myocardial Stunning / Q000503:physiopathology; D011446:Prospective Studies; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors; D016277:Ventricular Function, Left