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Aim:To investigate effects of icariin on cardiac gene expression and the modula-tion of nitric oxide(NO)signal transduction during the differentiation of embry-onic stem(ES)cells into cardiomyocytes in vitro.Methods:The expression levelsof cardiac developmental-dependent genes were measured using reverse tran-scription-polymerase chain reaction(RT-PCR).The chronotropic responses ofcardiomyocytes to β-adrenoceptor stimulation were determined.The levels ofcAMP and cGMP in ES cells were measured using radioimmunoassay.Endog-enous NO levels were measured by using the Griess reaction.Aminoguanidine(AG)was used to confirm the influence of icariin on the endogenous NO signalpathway.Results:Icariin significantly elevated mRNA levels of cardiac tran-scription factors GATA4 and Nkx2.5,and cardiac-specific α-MHC,MLC-2v and β-AR genes in a concentration-and time-dependent manner(P<0.05).Cardiomyo-cytes derived from embryoid body(EB)treated with icariin were more sensitive toisoprenaline(P<0.01).Treatment of ES cells with icariin resulted in a continuedelevation in the cAMP/cGMP ratio before a shift to the cardiomyocyte phenotype(P<0.05).AG decreased the NO level,and delayed and decreased the incidence ofcontracting EB to only approximately 35% on d 5+11,an effect that could berescued by icariin.When cells were cocultured with icariin and AG,the percentageof beating EB reached a peak level of 73% on d 5+11(P<0.05),Conclusion:Theinducible effects of icariin were partly related to increase in the expression ofcardiac developmental-dependent genes,and elevation of the cAMP/cGMP ratioin ES cells,as well as upregulation of endogenous NO generation during the earlystages of cardiac development.
Aim: To investigate effects of icariin on cardiac gene expression and the modula-tion of nitric oxide (NO) signal transduction during the differentiation of embry-onic stem (ES) cells into cardiomyocytes in vitro. Methods: The expression levels of cardiac developmental-dependent genes were measured using reverse tran-scription-polymerase chain reaction (RT-PCR). The chronotropic responses ofcardiomyocytes to β-adrenoceptor stimulation were levels of cAMP and cGMP in ES cells were measured using radioimmunoassay. Endog-enous NO levels were measured by using the Griess reaction. Aminoguanidine (AG) was used to confirm the influence of icariin on the endogenous NO signal pathway. Results: Icariin higher elevated mRNA levels of cardiac tran-scription factors GATA4 and Nkx2.5, and cardiac-specific alpha-MHC , MLC-2v and β-AR genes in a concentration-and time-dependent manner (P <0.05) .Cardiomyo-cytes derived from embryoid body (EB) treated with icariin were more sensitive to isoprenaline (P <0.01) . Treatment of ES cells with icariin resulted in a continue delevation in the cAMP / cGMP ratio before a shift to the cardiomyocyte phenotype (P <0.05). AG decreased the NO level, and delayed and decreased the incidence of conducting EB to only about 35% on d 5 + 11, an effect that could be becued by icariin. When cells were cocultured with icariin and AG, the percentage of beating EB reached a peak level of 73% on d 5 + 11 (P <0.05), Conclusion: Theinducible effects of icariin were partly related to increase in the expression of cardiac developmental-dependent genes, and elevation of the cAMP / cGMP ratio in ES cells, as well as upregulation of endogenous NO generation during the early stages of cardiac development.