title: Intra-myocyte ion homeostasis during ischemia-reperfusion injury: effects of pharmacologic preconditioning and controlled reperfusion.
abstract: BACKGROUND
  This study determines whether controlled reperfusion or diazoxide improves intramyocyte Na(+) homeostasis using a porcine model of severe ischemia-reperfusion injury.
  
  
  METHODS
  Three groups (n = 10 pigs per group) had 75 minutes of left anterior descending artery occlusion during bypass. Group 1 had no treatment (control group), group 2 had controlled reperfusion (500 mL warm cardioplegia) (controlled reperfusion group), and group 3 had diazoxide (50 micromol/L before left anterior descending artery occlusion) (diazoxide group). Biopsies were taken from the left anterior descending artery region before ischemia and at 3, 5, and 10 minutes postreperfusion. Intra-myocyte Na(+) and water contents were determined using atomic absorption spectroscopy, and Na(+) concentrations were calculated.
  
  
  RESULTS
  Intra-myocyte Na(+) increased for the diazoxide group pigs at 3-minutes postreperfusion (21.9 +/- 2.9 vs 34.0 +/- 3.4 micromol/mL; p = 0.02), but decreased to 19.9 +/- 3.2 micromol/mL at 10 minutes postreperfusion (p = 1.0 vs baseline). At 10 minutes postreperfusion, intra-myocyte Na(+) in the controlled reperfusion group was lower than baseline (22.3 +/- 2.7 vs 17.2 +/- 3.1 micromol/mL; p < 0.001). Intra-myocyte Na(+) at 10 minutes postreperfusion for the diazoxide and controlled reperfusion groups was lower than for the control group (p < 0.05).
  
  
  CONCLUSIONS
  Diazoxide and controlled reperfusion improved intra-myocyte Na(+) homeostasis after severe ischemia-reperfusion injury.
authors.affiliation: Department of Surgery, Birmingham, University of Alabama at Birmingham, 35294, USA.
authors.forename: James E
authors.initials: JE
authors.lastname: Davies
authors.forename: Stanley B
authors.initials: SB
authors.lastname: Digerness
authors.forename: Steven P
authors.initials: SP
authors.lastname: Goldberg
authors.forename: Cheryl R
authors.initials: CR
authors.lastname: Killingsworth
authors.forename: Charles R
authors.initials: CR
authors.lastname: Katholi
authors.forename: Paul S
authors.initials: PS
authors.lastname: Brookes
authors.forename: William L
authors.initials: WL
authors.lastname: Holman
mesh_terms: D000818:Animals; D003981:Diazoxide / Q000494:pharmacology*; D005260:Female; D006706:Homeostasis / Q000187:drug effects / Q000502:physiology*; D019157:Ischemic Preconditioning, Myocardial / Q000379:methods*; D008297:Male; D015425:Myocardial Reperfusion / Q000379:methods*; D032383:Myocytes, Cardiac / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism; D013552:Swine; D014882:Water-Electrolyte Balance / Q000187:drug effects / Q000502:physiology*
chemical_list: D012964:Sodium; D003981:Diazoxide