ABSTRACT
AIM:To observe the effect of B-HT933, a selective α2-adrenoceptor agonist, on lipopolysaccha-ride ( LPS )-induced TNF-αproduction in neonatal rat cardiomyocytes and to explore the underlying mechanisms . METHODS:The neonatal rat cardiomyocytes were cultured .The localization of α2A-adrenoceptor in the cardiomyocytes was examined by immunofluorescence staining .The cardiomyocytes were exposed to LPS or/and B-HT933 for different time.The level of TNF-αin the supernatants and the mRNA expression of TNF-αwere detected by ELISA and real-time PCR, respectively.In addition, LPS-associated signal molecules in the cardiomyocytes were also examined by Western blotting.RESULTS: Immunofluorescence staining showed that α2A-adrenoceptors were localized in the cardiomyocytes . LPS stimulated TNF-αproduction in the cardiomyocytes in a dose and time-dependent manner .B-HT933 pretreatment sig-nificantly inhibited the expression of TNF-αat mRNA and protein levels in LPS-treated cardiomyocytes .Furthermore, LPS exposure induced IκBαand p38 phosphorylation in cardiomyocytes and only IκBαphosphorylation was prevented by B-HT933 treatment.CONCLUSION:α2A-adrenoceptors are present in neonatal rat cardiomyocytes and its agonist B -HT933 inhibits LPS-induced TNF-αproduction in cardiomyocytes via suppressing IκBαphosphorylation .