OBJECTIVEThe effects of various postconditioning algorithm on reperfusion injury and the role of mitochondrion pathway were investigated in a rat model of reperfusion/injury.

METHODSRats were divided into 5 groups: sham, reperfusion/injury (R/I group), reverse algorithm of postconditioning (R-Post, 30/10-25/15-15/25-10/30 s of reperfusion/re-occlusion), standard algorithm of postconditioning (S-Post, 4 cycles of 20/20 s of reperfusion/re-occlusion), and gradual algorithm of postconditioning (G-Post, 10/30-15/25-25/15-30/10 s of reperfusion/re-occlusion).

RESULTSThe levels of Bax, Cytochrome-c, Caspase-9, serum marker of myocardium and apoptosis index were significantly lower while the level of Bcl-2 was significantly higher in the three postconditioning groups than those in R/I group (all P < 0.05). The levels of Bax (0.35 +/- 0.10 vs. 0.50 +/- 0.02, P < 0.05), Cytochrome-c (0.66 +/- 0.16 vs. 1.68 +/- 0.22, P < 0.05), Caspase-9 (0.61 +/- 0.17 vs. 1.66 +/- 0.55, P < 0.05), serum marker of myocardium [CK: (251.00 +/- 45.16) U/L vs. (388.56 +/- 75.01) U/L, P < 0.05; CK-MB: (146.00 +/- 60.12) U/L vs. (291.16 +/- 52.41) U/L, P < 0.05] and apoptosis index [(4.32 +/- 1.16)% vs. (8.58 +/- 1.12)% , P < 0.05] were all significantly lower while Bcl-2 level (2.00 +/- 0.34 vs. 1.40 +/- 0.18, P < 0.05) was significantly higher in G-Post group than those in S-Post group. Moreover, above mentioned cardiac protective effects were significantly stronger in the G-Post group compared to R-Post group (all P < 0.05).

CONCLUSIONIn conclusion, gradual algorithm of postconditioning could attenuate reperfusion injury more significantly than standard algorithm, and mitochondrion pathway plays an important role in this cardioprotective process.