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Acta Physiologica 2011; Volume 201, Supplement 682
The 90th Annual Meeting of The German Physiological Society
3/26/2011-3/29/2011
Regensburg, Germany
POSTCONDITIONING PROTECTS CARDIOMYOCYTES AGAINST REPERFUSION INJURY BY INHIBITING MITOCHONDRIAL PERMEABILTY TRANSITION PORE AND DELAYING PH RECOVERY IN EARLY REPERFUSION
Abstract number: O39
*Shahzad1 T., Iraqi2 W., Kasseckert2 S.A., Micoogullari2 M., Scharbrodt1 W., Ortel1 M., Schluter2 K.-D., Piper3 H.M., Abdallah4 Y.
Question:
Studies in vivo have shown that postconditioning of ischemic heart confers protection against reperfusion injury. The aim of the present study was to establish a postconditioning protocol in a cell culture model of ischemia and reperfusion to study the cellular signalling of postconditioning. We hypothesize that postconditioning inhibits opening of the mitochondrial permeability transition pore (MPTP) and delays the pH recovery upon reperfusion.
Methods:
To simulate ischemia and reperfusion, isolated cardiac myocytes from adult rat were superfused anoxically (pH 6.4; no glucose; 100% N2) and then reperfused with a normoxic puffer (pH 7.4; glucose; 21% O2). Postconditioning, i.e., repetitive cycles of anoxic and normoxic perfusion, was applied during the first minutes of reperfusion. Loss of mitochondrial membrane potential (?y) as an indicator for MPTP opening, cytosolic Ca2+ concentration, cellular pH and necrosis were measured by the use of JC-1, Fura-2, BCECF-ratio and propidium iodide respectively.
Results:
Simulated ischemia led to depolarization of mitochondrial membrane potential (?y), and an increase in cytosolic Ca2+ and acidification of the cells. During the first two minutes of reperfusion, ?y recovered to pre-anoxic value, but collapsed after 5 min of reperfusion. The cells developed severe cytosolic Ca2+ oscillations, contracture and necrosis. In postconditioned cells, collapse in ?y (?yi[%] :Ctr:144±29% vs PC: 306±27%* compared to ?y at the start of reperfusion(100%); n>=66 cells each condition), contracture (cell length [%]: Ctr: 48% vs PC: 67%*; n>= 32 cells each condition), cytosolic Ca2+ oscillations (Fura-2 ratio [a.u.]: Ctr: 75/min vs PC: 25/min*; n>= 35 cells each condition) and necrosis (necrosis [%]: Ctr: 36% vs PC: 20%*; n>= 230 cells each condition) were significantly prevented and the pH recovery was delayed and improved (BCECF ratio [490/440nm] :Ctr: 81±3.3 vs PC: 96±2.7*) [*p < 0.05 vs control].
Conclusions:
Postconditioning prevents reperfusion injury by inhibiting the opening of MPTP and delaying the pH recovery in the early reperfusion.
To cite this abstract, please use the following information:
Acta Physiologica 2011; Volume 201, Supplement 682 :O39