SPECIAL PROCESSED PANAX GINSENG (SPPG) RELAXES ISOLATED RABBIT CORPUS CAVERNOSUM THROUGH HISTAMINE ANTAGONIZED PROPERTY AND WITH A BENEFICIAL EFFECT IN RAISING INTRACAVERNOUS PRESSURE

The in vitro and in vivo effects of special processed Panax ginseng (SPPG) in rabbit corpus cavernosum were investigated. SPPG induced a concentration-dependent relaxation in phenylephrine-precontracted cavernosal strips with an EC50 of 0.39 ± 0.06 mg/ml and turned out to be more potent than total ginsenosides (1.33 ± 0.09 mg/ml). Comparison the HPLC profile of SPPG with 7 major ginsenoside standards indicated that Rg1, Rf and Rc, with a percentage of 65, 20, and 2.5%, respectively, were the predominant component and pre-cluding the involvement of Rb1, Rb2, Rd, and Re. The corporal relaxation of SPPG may be mediated by component(s) in addition to Rg1/Rf/Rc because a reconstituted mixture did not mimic the potent relaxant effect of SPPG. Neither endothelial removal nor L-NAME treatment affect SPPG-induced relaxation. Histamine (10^(-8)-10^(-4) M) produced concentration-dependent contraction of cavernosal strips. The contractile response to histamine was progressively suppressed both by H1-receptor antagonist triprolidine and by SPPG (1, 2 and 4 mg/ml). On the other hand, SPPG-induced relaxation of phenylephrine-precontracted cavernosal strips was not attenuated by H2 receptor antagonist cimetidine. Intracavernous (IC) injection of SPPG (0.5, 1, 2 and 4 mg/ml) to anesthetized rabbits, rose the IC pressure from basal (13.7 ± 4.2 mmHg) to19.2 ± 5.4, 34.6 ± 4.2, and 46.7 ± 8.2 mmHg, respectively and prolonged the duration of tumescence ranged from 20 to 90 min. These finding indicate that non-major ginsenosides contribute to the beneficial corporal relaxant effect of SPPG, which is attributable to an endothelium-independent properties possibly link to antagonizing the H1 receptor in the cavernosal smooth muscle. Furthermore, the in vivo effects of SPPG may implicate a potential for the treatment of erectile dysfunction.