OBJECTIVE: To investigate the protective effects of ISO on cardiomyocyte injury induced by lipopolysaccharide (LPS) in H9c2 cells. MATERIALS AND METHODS: Cell viability was determined using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The activities of LDH and CK in the supernatant of H9c2 cells with different treatments were determined using colorimetric assays to assess the conversion of pyruvic acid to lactic acid by LDH and that of triphosphate and creatine to phosphagen by CK. RESULTS: ISO significantly enhanced cell viability and alleviated the release of lactate dehydrogenase and creatine phosphate kinase in a dose-dependent manner in H9c2 cells treated with LPS. However, the protective effects of higher doses of ISO (1.4% and 2.1%) had no significant difference. Thus, 1.4% ISO was selected for subsequent experiments. ISO inhibited LPS-induced inflammatory responses, as evidenced by reduced expression of tumor necrosis factor-a, interleukin (IL)-1 beta, and IL-6; it also attenuated the activation of nuclear factor (NF)-kB p65, and the inhibition of NF-kB p65 DNA-binding activity in H9c2 cells. ISO also suppressed oxidative stress and enhanced antioxidant defense in LPS-treated H9c2 cells, as determined by decreased levels of reactive oxygen species and malondialdehyde, increased production of glutathione reductase, and enhanced superoxide dismutase and glutathione peroxidase activities. Moreover, ISO inhibited LPS-induced H9c2 cell apoptosis, as shown by reduced caspase-3 activity; down-regulated expression of the pro-apoptotic procaspase-3, cleaved caspase-3, and Bax; and upregulated expression of the anti-apoptotic Bcl-2. CONCLUSIONS: These findings indicate that ISO reduced LPS-induced H9c2 cell injury via anti-inflammatory, anti-oxidative, and anti-apoptotic activities; hence, ISO may be an alternative therapy for septic heart injury.