Effects of aging on ischemic tolerance and a role of cell-cycle regulating proteins in ischemic myocardium

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Effects of left ventricular (LV) Mechanical unloading on ischemic tolerance in post-MI hearts1)Myocardial infarction (MI) was Induced by ligating the left anterior descending coronary artery (LAD) of rat hearts.2)Two weeks after the LAD ligation, heterotopic heart transplantation was done by anastomosing the ascending aorta of the donor to the recipient's abdominal aorta, and the pulmonary artery to the inferior vena cava, respectively.3)Two weeks after LV unloading, donor hearts were explanted and were subjected to Langendorff perfusion.4)The hearts received 30 minutes of global ischemia and 60 Minutes of reperfusion.5)Post ischemic LV developed pressure in unloaded hearts was higher than that in untreated MI hearts.Change in expression of cell-cycle regulation proteins in post MI hearts1)MI was produced by ligating the LAD in 8-months old rats.2)The hearts were explanted after three days, one week, two weeks and four weeks after the LAD ligation respectively.3)The mRNA of cyclin D1, cyclin D3, Cdk2, Cdk4, Cdk6, and PCNA in each sample was quantified by the real-time RT-PCR.4)The mRNA of PCNA and CDK4 in 8-months old rats showed higher value three days and two weeks after MI.Effects of aging on expression of cell-cycle regulating proteins1)MI was produced by ligating the LAD fn 40-months old rats.2)The hearts were explanted after three days, one week, two weeks and four weeks after the LAD ligation.3)The mRNA of cyclin D1, cyclin D2, cyclin D3, Cdk2, Cdk4, Cdk6, and PCNA in each sample was quantified by the real-time RT-PCR.4)No change in above parameters was observed in 40-months old MI rats