Abstract: Objective To analyze the influence of ischemic postconditioning (IP) on cardiacfunction, myocardial apoptosis and expressions of myocardial tissue mitochondrial apoptosis-relatedmolecules in rats with myocardial ischemia-reperfusion (IR). Methods Forty 8-week-old male SDrats were fed in separate cages with 5 rats in each cage for 7 days of adaptive feeding, and were randomly divided into 4 groups: blank control group ( control group), sham operation group ( S group), myocardial IR model group ( IR group) and myocardial IR model + IP treatment group (IP group), with 10 rats in each group. At 4 hours after surgery, the cardiac function indicators [left ventricular systolic pressure ( LVSP), left ventricular end-diastolic pressure ( LVEDP), maximum rate of left ventricular pressure change ( ± dp / dtmax)] were recorded by biological functional system, and the apoptosis of myocardial cells was detected by TUNEL method. RT-PCR was used to detect the relative expression levels of myocardial apoptosis-related proteins BCL-2, BAX, cysteinyl aspartate specific protease-3 ( Caspase-3), farnesoid X receptor ( FXR) and small heterodimer partner (SHP). Western blotting was applied to detect the release of myocardial mitochondrial apoptosis pathway marker cytochrome C ( Cyt-C). Results The LVEDP, apoptosis index ofmyocardial cells, and the expression levels of BAX, CASPASE-3, FXR and SHP in myocardial tissues and the expression level of Cyt-C protein in myocardial cytoplasm were higher in the IP andIR groups than those in the S and control groups ( P < 0. 05), moreover, the above indicators in the IR group were higher than those in the IP group (P < 0. 05). The LVSP, ± dp / dtmax and theexpression level of BCL-2 in myocardial tissues in the IP group and IR group were lower than thosein the S group and control group (P< 0. 05), and the above indicators were lower in the IR group than those in the IP group (P < 0. 05). Conclusion IP treatment can alleviate the myocardial IRinjury and improve the cardiac function in rats, which may be related to the regulations of apoptosisrelated signal proteins such as BCL-2 / BAX and FXR / SHP.

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