THE RELAXATION EFFECTS OF GINSENG SAPONIN IN RABBIT CORPORAL SMOOTH-MUSCLE - IS IT A NITRIC-OXIDE DONOR

Objective To determine whether crude extracts of ginseng saponin (GCS) , containing the active ingredients from Panax ginseng and used as an aphrodisiac in oriental countries, relax corpus cavernosal smooth musc le in the rabbit. Materials and methods Corpus cavernosal strips were prepared from rabbit penises. Isometric tension changes, recorded with a pressure transducer, in response to various drugs and electrical st imulation were assessed in an organ chamber. after active muscle tone had been induced by 10 mu mol/L phenylephrine. Results GCS (0.2-8.0 mg ) relaxed the smooth muscle of rabbit corpus cavernosum (SMRCC) pre-co ntracted with phenylephrine in a dose-dependent manner. GCS at 0.75 mg significantly enhanced the relaxation of SMRCC induced by electrical field stimulation. The relaxation induced by 0.2-8.0 mg GCS was signif icantly attenuated by atropine (1 mu mol/L), methylene blue (100 mu mo l/L) and N-omega-nitro-L-arginine methyl ester (L-NAME, 10 mu mol/L). However, there was no significant difference in the attenuation of GCS -induced relaxation of SMRCC by adding vasoactive intestinal peptide a ntagonists or indomethacin. In addition, the decreasing rate of GCS-in duced relaxation of SMRCC by methylene blue and L-NAME was greater tha n that by atropine. L-arginine (10 mmol/L) reversed the inhibitory eff ect induced by L-NAME (1 mmol/L) on the attenuation of GCS-induced rel axation. Conclusions These data suggest that GCS, as a nitric oxide do nor, induces the relaxation of SMRCC through the L-arginine/nitric oxi de pathway. For the clinical application of ginseng saponin, further s tudies are required to clarify the active subfraction(s) of GCS.