AIM: To study the effects and mechanisms of norepinephrine (NE) on the activity of nuclear factor-kappa B (NF-?B) in cardiomyocytes. METHODS: Using the cultured neonatal rat cardiac myocytes, the levels of reactive oxygen species and the nuclear DNA binding activity of NF-?B were measured in cardiomyocytes before and after stimulated with NE alone, NE+prazosin+propranolol, and NE+vitamin E, respectively. RESULTS: NE increased significantly the levels of reactive oxygen species and NF-?B activity in cardiac myocytes. These effects of NE were attenuated by vitamin E pretreatment, as well as prazosin and propranoloe. CONCLUSION: The effects of NE on cardiomyocytes might be exerted partly through NF-?B activation, and associated with NE-induced overproducion of reactive oxygen species via the adrenergic receptor pathway. [