Objective To investigate the expression of non-phagocytic cell oxidase (Nox), reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, in mice of lipopolysaccharide (LPS)-induced acute myocardial injury and its significance. MethodsSPF male C57/BL6 mice (8-10 weeks old) were randomly assigned into control group (normal saline,n=15) and LPS group (n=15). LPS group was injected with large dose of LPS (10 mg/kg) to induce acute myocardial injury model, and the control group was only injected with saline equivalent. The mice were sacrificed in 6 h later, and the heart tissues were harvested. The mRNA and protein levels of Nox 2, Nox 4, Bcl-2-associated X protein (Bax), B cell lymphoma/leukemia-2 (Bcl-2) and cysteine aspastic acid-specific protease 3 (Caspase 3) were detected by RT-PCR and Western blotting respectively. The expression of lipid peroxidation products (4-HNE) in the myocardium was measured by immunohistochemistry. TUNEL was used to detect myocardial apoptosis. SPSS statistics 13.0 was used to perform the statistical analysis, and student’s t test was employed for comparison between groups. ResultsCompared with the control group, the mRNA and protein levels of Nox 2, Nox 4 and Bax were significantly increased, while those of Bcl-2 were decreased, and the protein expression of Caspase 3 was elevated in the LPS group (P<0.05). Immunohistochemical assay showed that the expression of 4-HNE was significantly higher in the mice of the LPS group (P<0.05). TUNEL assay indicated that there were more apoptotic cells in the LPS group (P<0.05). Conclusion NADPH oxidase takes part in the occurrence and development of acute myocardial injury through regulating oxidative stress and cell apoptosis.