Hypothermic injury: the mitochondrial calcium, ATP and ROS love-hate triangle out of balance.
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.
Brinkkoetter
Paul-Thomas
PT
Vth Medical Department, University Hospital of Mannheim, University of Heidelberg, Mannheim, Germany.
Song
Hui
H
Lösel
Ralf
R
Schnetzke
Ulf
U
Gottmann
Uwe
U
Feng
Yuxi
Y
Hanusch
Christine
C
Beck
Grietje C
GC
Schnuelle
Peter
P
Wehling
Martin
M
van der Woude
Fokko J
FJ
Yard
Benito A
BA