title: Hypothermic injury: the mitochondrial calcium, ATP and ROS love-hate triangle out of balance.
abstract: OBJECTIVE
  Catecholamines prevent hypothermic cell death which accounts for severe tissue damage and impaired allograft function after prolonged organ preservation. Here, we identified cellular processes which govern hypothermia-mediated cell death in endothelial cells and how they are influenced by dopamine.
  
  
  METHODS
  Lactate dehydrogenase assay, intracellular ATP, reactive oxygen species and reduced thio-group measurement, intracellular calcium measurement and mitochondrial calcium staining were performed in the study.
  
  
  RESULTS
  Intracellular ATP was almost completely depleted within 12 hrs of hypothermic preservation in untreated human umbilical vein endothelial cells (HUVEC), while dopamine pre-treatment significantly delayed ATP depletion. 4 hrs after hypothermia a redox imbalance was observed in untreated cells, which increased with the duration of hypothermia. The redox imbalance was primarily caused by depletion of SH reduction equivalents and was significantly inhibited by dopamine. In addition, hypothermia-induced Ca(2+) influx and mitochondrial Ca(2+) accumulation were both prevented by dopamine. The protective effect of dopamine was abrogated by ionomycin and sodium azide and partly by oligomycin and CCCP.
  
  
  CONCLUSIONS
  Our data demonstrated that loss of intracellular ATP, generation of a redox imbalance and accumulation of intracellular Ca(2+) underlie cold preservation injury. Dopamine improves the redox balance, prevents intracellular Ca(2+) accumulation and delays ATP depletion.
authors.affiliation: Vth Medical Department, University Hospital of Mannheim, University of Heidelberg, Mannheim, Germany.
authors.forename: Paul-Thomas
authors.initials: PT
authors.lastname: Brinkkoetter
authors.forename: Hui
authors.initials: H
authors.lastname: Song
authors.forename: Ralf
authors.initials: R
authors.lastname: Lösel
authors.forename: Ulf
authors.initials: U
authors.lastname: Schnetzke
authors.forename: Uwe
authors.initials: U
authors.lastname: Gottmann
authors.forename: Yuxi
authors.initials: Y
authors.lastname: Feng
authors.forename: Christine
authors.initials: C
authors.lastname: Hanusch
authors.forename: Grietje C
authors.initials: GC
authors.lastname: Beck
authors.forename: Peter
authors.initials: P
authors.lastname: Schnuelle
authors.forename: Martin
authors.initials: M
authors.lastname: Wehling
authors.forename: Fokko J
authors.initials: FJ
authors.lastname: van der Woude
authors.forename: Benito A
authors.initials: BA
authors.lastname: Yard