Ginsenosides Rb1 and Re decrease cardiac contraction in adult rat ventricular myocytes:: role of nitric oxide

1 Panax ginseng is used to enhance stamina and relieve fatigue as well as physical stress. Ginsenoside, the effective component of ginseng, regulates cardiovascular function. This study was to examine the effect of ginsenosides Rb-1 and Re on cardiac contractile function at the cellular level. Ventricular myocytes were isolated from adult rat hearts and were stimulated to contract at 0.5 Hz. Contractile properties analysed included: peak shortening (PS), time-to-90%PS (TPS), time-to-90% relengthening (TR90), and fluorescence intensity, change (Delta FFI) Nitric oxide synthase (NOS) activity was determined by the H-3-arginine to IH-citrulline conversion assay. 2 Both Rb-1 and Re exhibited dose-dependent (1 - 1000 nm) inhibition in PS and Delta FFI, with maximal inhibitions between 20-25%. Concurrent application Rb-1 and Re did not produce any additive inhibition on peak shortening amplitude (with a maximal inhibition of 24.9 +/-6.1%), compared to Rb-1 or Re alone. Pretreatment with the NOS inhibitor N-nitro-L-arginine methyl ester (L-NAME, 100 mum) abolished the effect of Rbl and Re. Both Rb-1 and Re significantly (P <0.05) stimulated NOS activity concentration-dependently. 3 This study demonstrated a direct depressant action of ginsenosides on cardiomyocyte contraction, which may be mediated in part through increased NO production.