Cardiomyocytes undergo apoptosis in response to ischemia and ischemia/reperfusion (I/R). During heart preservation, inhibition of apoptosis is critical to avoid organ failure. We aimed to compare the protection afforded by Celsior (Cs) and Histidine buffer solution (HBS) against apoptotic signaling in hearts subjected to moderate (4 h) versus severe (6 h) ischemia alone or followed by 30 min reperfusion. The impact of gender on cardioplegic protection was also explored. Hearts from male and female Wistar-Han rats were divided by gender in distinct groups: control, perfusion_control, ischemia, and I/R. Ischemia and I/R groups were divided in subgroups Cs or HBS, and subjected to 4 or 6 h ischemia alone or followed by reperfusion. Proteins involved in apoptotic signaling (p53, Bax, Fas, FasL, and Flip) were quantified by Western blot in mitochondria and/or whole tissue. Caspases 3, 8, and 9-like activities were measured and hemodynamic parameters were monitored. Ischemia activated p53/Bax signaling. After I/R, HBS-preserved hearts had lower p53/Bax content in mitochondrial fractions than Cs-preserved hearts. The p53/Bax decrease in tissue samples was mostly observed in females. Caspase 3-like activity was increased in HBS-preserved male hearts. The heart rate was decreased in Cs and HBS-preserved hearts. Fas protein levels remained unaltered in all conditions but soluble FasL increased from 4 to 6 h preservation in Cs and HBS. Hearts from male rats were more prone to apoptosis and myocardial dysfunction. HBS and Cs were not effective in inhibiting apoptotic signaling although HBS presented best overall results. Both solutions should be improved to prevent apoptosis and myocardial dysfunction after I/R.
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