Objective   To investigate the effect of ischemic preconditioning (IP) on the content of myocardial mitochondria cardiolipin and the heart function in isola

ted rat hearts.    Methods   Seventy-two healthy SD rats of both sexes (36 males

36 females) weighing 200 to 300 g were randomly divided into 4 groups (n=18 for each group): normal group

control group

IP group (IP) and 5-hydroxydecanoate (5-HD) plus IP group (HD). Langendorff apparatus were used to establish the model of ischemia/reperfusion in isolated rat hearts. The hearts were perfused for 20 min to get stabilization followed by continuous perfusion in normal group for 100 min. In control group

after perfusing of 20 min for stabilization followed by continuous perfusion for 30 min

the hearts were then reperfused for 30 min after 40 min ischemia. In IP group

the hearts were given a 5-minute ischemia and 5-minute reperfusion for twice in order within a brief intermittent period

and ischemia reperfusion was carried out in the same way as that in control group. In HD group

the hearts were perfused with 100 μmol/L 5-HD before IP

and the following procedures were carried out as those in IP group. HR

left ventricular end-diastolic pressure (LVEDP)

left ventricular developed pressure (LVDP) were recorded at the end of stable perfusion (T

1

)

immediately before ischemia (T

2

) and at the end of reperfusion (T

3

) in all the groups. The content of myocardial mitochondria cardiolipin was measured with HPLC.    Results   When the parameters at T

3

were compared with those at T

1

and T

2

HR and LVDP were decreased

LVEDP was increased and the content of myocardial mitochondria cardiolipin was decreased. All these changes were significant (P0.05

P0.01). The changes mentioned above were also significant at T

3

in control

IP and HD groups than in normal group (P0.05，P0.01). Conversely

HR and LVDP were increased

LVEDP was decreased

and the content of myocardial mitochondria cardiolipin became higher at T

3

in IP group than in control group and HD group (P0.05

P0.01). The values were also significant at T

3

in HD group tha

n in control group (P0.05

P0.01).    Conclusion   IP maintains the stable level of myocardial mitochondria cardiolipin and improves the cardiac function during ischemia/reperfusion in isolated rat hearts. The protective effect of IP probably may result from the activation of mitochondrial ATP sensitive potassium channels.