Objective     To study the protective effect of hydrogen sulfide (H

2

S) post-conditioning on hypoxia-reoxygenation injury in primary cultured cardiomyocytes from neonatal rats and its possible mechanism.      Methods      Sodium hydrosulfide (NaHS) was used as an exogenous donor of H

2

S. Primary cultured cardiomyocytes from neonatal rats were randomly divided into control group，hypoxia-reoxygenation (HR) group

dimethyl sulfoxide (DMSO) group

H

2

S post-conditioning group

and LY294002+H2S post-conditioning group. Survival rate of cardiomyocytes and activity of creatine kinase (CK) and lactate dehydrogenase (LDH) in cultured cardiomyocytes were assayed before hypoxia and 2 h after hypoxia-reoxygenation

respectively. Apoptosis in the cardiomyocytes was detected by flow cytometry and expression of hypoxia-inducible factor-1alpha (HIF-1α)

p-Akt and Akt protein was detected by Western blotting.      Results       In 2 h after reoxygenation

the survival rate of cardiomyocytes was significantly higher in H

2

S post-conditioning group than in HR group [(71.55±1.46)% vs (62.03±1.29)%

P0.01

]

but the activity of CK and LDH and the apoptosis in the cardiomyocytes were significantly lower in H

2

S post-conditioning group than in HR group[(244.99±21.38)U/L vs (329.53±26.14)U/L

(371.64±18.62)U/L vs (427.69±13.25)U/L

(10.37±1.51)% vs (17.38±2.04)%

P0.01

]

and the expression level of HIF-1αand p-Akt was significantly higher in H

2

S post-conditioning group than in HR group [(63.93±4.64)% vs (41.82±6.14)%

(62.59±2.11)% vs (41.04±4.01)%

P0.01

]

. However

after PI3K/Akt pathway inhibitor LY294002 was added during H

2

S post-conditioning

when compared with H

2

S post-conditioning group

the survival rate of cardiomyocytes was significantly lower (63.65±2.01) %

the activity of CK and LDH and the apoptosis of cardiomyocytes were significantly higher [(307.80±21.68)U/L

(421.51±15.95)U/L

(15.17±1.56)%

P0.01

]

and the expression level of HIF-1αand

p-Akt protein was markedly lower[(51.79±4.27)%

(47.42±3.15)%

P0.05 and P0.01

]

in LY+H

2

S group.      Conclusion       H

2

S post-conditioning promotes the expression of HIF-1α through the PI3K/Akt signaling pathway

thus protecting cardiomyocytes against myocardial ischemia-reperfusion injury.