Silencing of lncRNA GAS5 is able to protect H9c2 cells against HR injury. (A) H9c2 cells were transfected using siGAS5, and it was verified that the silencing efficiency reached 80%. **P<0.01 vs. the control. (B) Silencing of lncRNA GAS5 significantly improves cell viability as demonstrated by Cell Counting Kit 8 assays. (C) Release levels of LDH. (D) Release levels of CK-MB. *P<0.05, **P<0.01 and ***P<0.001 with comparisons shown by lines. n=3. Data are presented as the mean ± standard deviation. Control, cells with a normal culture; HR, cells with hypoxia/reoxygenation injury treatment; HR+transfection, cells with hypoxia/reoxygenation injury and transfection reagent only; HR+siNC, cells with hypoxia/reoxygenation injury and negative control transfection; HR+siGAS5, cells with hypoxia/reoxygenation injury and siRNA-GAS5 transfection; lncRNA, long non-coding RNA; GAS5, growth arrest specific 5; si/siRNA, small interfering RNA; NC, negative control; HR, hypoxia-reoxygenation; LDH, lactate dehydrogenase; CK-MB, creatine kinase isoenzyme; OD, optical density.