Protective Effects of Sphingosine-1-phosphate Postconditioning on Hypoxia / Reoxygenation Injury in Rat H9c2 Cardiomyocytes

ABSTRACT: OBJECTIVE To investigate protective effects and mechanism of sphingosine 1-phosphate (S1P) postconditioning on H9c2 cardiomyocytes exposed to hypoxia/reoxygenation injury. METHODS H9c2 cardiomyocytes were randomly divided into five groups: ①Control group；②Hypoxia /reoxygenation ( H/R) group；③S1P low concentration (L)group；④S1P midlle concentration (M) group；⑤S1P high concentration (H) group. The survival rates of cardiomyocytes were detected．The activity of superoxide dismutase (SOD) and the content of malondialdehyde (MDA) in the culture medium was measured．The apoptotic percentage was measured with flow cytometry. The free intracellular calcium ions were labeled by Fura 2-AM and the fluorescent intensity produced by Fura 2-AM was measured，which reflected the changes of the concentration of the free intracellular calcium ions．Western blot was performed to examine expression of heat shock protein 70 (HSP70) in cardiomyocytes respectively. RESULTS S1P could protect H9c2 cardiomyocytes against hypoxia/eoxygenation injury , increase cell survival rate, decrease the content of MDA and free intracellular calcium, increase the activity of SOD, increase the expression of HSP70, with a certain concentration dependent manner. CONCLUSION S1P could reduce hypoxia/reoxygenation-induced oxidative stress in cardiac myocytes, improve myocardial viability and reduce the apoptotic rate．The mechanism may depend on reduce intracellular calcium overload , increase the expression of HSP70．