Effects of ginsenoside on large-conductance KCa channels in human corporal smooth muscle cells

Characterization and functional roles of KCNQ-encoded voltage-gated potassium (Kv7) channels in human corpus cavernosum smooth muscle

The group of KCNQ-encoded voltage-gated potassium (Kv7) channels includes five family members (Kv7.1-7.5). We examined the molecular expression and functional roles of Kv7 channels in corporal smooth muscle (CSM). Isolated rabbit CSM strips were mounted in an organ bath system to characterize Kv7 channels during CSM relaxation. Intracellular Ca²⁺ levels were measured in the CSM using the Ca²⁺ dye Fluo-4 AM. The expression of the KCNQ1-5 (the encoding genes for Kv7.1-7.5) and KCNE1-5 subtypes was determined by quantitative real-time PCR. Electrophysiological recordings and an in situ proximity ligation assay (PLA) were also performed. ML213 (a Kv7.2/7.4/7.5 activator) exhibited the most potent relaxation effect. XE911 (a Kv7.1-7.5 blocker) significantly inhibited the relaxation caused by ML213. Removal of the endothelium from the CSM did not affect the relaxation effect of ML213. H-89 (a protein kinase A inhibitor) and ESI-09 (an exchange protein directly activated by cAMP inhibitor) significantly inhibited ML213-induced relaxation (H-89: 31.3%; ESI-09: 52.7%). XE991 significantly increased basal [Ca²⁺]_i in hCSM cells. KCNQ4 (the Kv7.4-encoding gene) and KCNE4 in CSM were the most abundantly expressed subtypes in humans and rats, respectively. KCNQ4 and KCNE4 expression was significantly decreased in diabetes mellitus rats. ML213 significantly increased the outward current amplitude. XE991 inhibited the ML213-induced outward currents. ML213 hyperpolarized the hCSM cell membrane potential. Subsequent addition of XE991 completely reversed the ML213-induced hyperpolarizing effects. A combination of Kv7.4 and Kv7.5 antibodies generated a strong PLA signal. We found that the Kv7.4 channel is a potential target for ED treatment.

Erectile dysfunction treatment and traditional medicine-can East and West medicine coexist?

Erectile dysfunction (ED) is a common sexual problem affecting many men irrespective of cultures, beliefs and nationalities. While medical therapy for ED has been revolutionized by the advent of oral phosphodiesterase type 5 inhibitors and intracavernosal injection of vasoactive agents, recent technological advances such stem cell therapy, low intensity shock wave and newer generation of penile prosthesis implant offer hope to men who do not respond to conventional medical therapy. In contrast, traditional and complementary medicine (TCM) focuses on the restoration and better overall bodily regulation with the use of various herbal and animal products as well as exercises to invigorate qi (energy) in vital organs. Western medicine involves an analysis of ED symptom and underlying causes that contribute to ED, while TCM emphases the concept of holism and harmonization of body organs to achieve natural sexual life. The following article reviews our current understanding regarding the philosophical approach, and evaluates the evidence surrounding various ED therapies between mainstream Western Medicine and TCM.

Current Status and Clinical Studies of Oriental Herbs in Sexual Medicine in Korea

Erectile dysfunction (ED) is one of the most common diseases among aging men. Although previous studies have shown that type 5 phosphodiesterase inhibitors (PDE5-Is) are very effective for the treatment of ED, many researchers are currently attempting to identify therapeutic agents from natural sources with comparable or better effects than PDE5-Is. Herbal medicine is thought to be advantageous because it is natural; moreover, it not only treats isolated symptoms, but also maintains general well-being. Furthermore, since newly created chemical compound libraries have limited structural diversity with regard to pharmaceutical agents, more attention has recently been paid to the ability of oriental herbs to enhance physical health, including sexual function. Herein, we review the current status of Korean preclinical or clinical studies of the application of oriental herbs to sexual medicine.

Effect of the novel BKCa channel opener LDD175 on the modulation of corporal smooth muscle tone

INTRODUCTION

The BKCa channel has been reported to play an important role in erectile function. Recently, novel BKCa channel activator, LDD175, was introduced.

AIM

This study aims to investigate whether LDD175 relaxes corporal smooth muscle (CSM) via BKCa channel activation.

METHODS

After isolation of CSM strip from a male rabbit model, contraction studies using organ bath was performed. Isolating human tissue and cell cultures, electrophysiological studies were done via whole-cell patch-clamp recording.

MAIN OUTCOME MEASURES

Vasodilatory effects of LDD175 were evaluated by cumulative addition ranging from 10(-7) to 10(-4) M in corpus cavernosal strips after precontraction with 10(-5) M phenylephrine via organ bath system. Using cultured human CSM cells, patch-clamp recording was performed. Erectile function was measured by in vivo rat cavernous nerve stimulation.

RESULTS

LDD175 caused an endothelium-independent relaxation of corporal tissues, and this effect was abolished by pretreatment with iberiotoxin. The relaxation effect of 10(-4) M LDD175 was greater than that of 10(-6) M udenafil (54.0 ± 3.1% vs. 34.5 ± 3.9%, P < 0.05); 10(-5) M LDD175 with 10(-6) M udenafil caused a greater relaxation effect on strips than 10(-5) M LDD175 or 10(-6) M udenafil alone (50.7%, 34.1%, vs. 20.7%, respectively, P < 0.001). In patch-clamp recordings, LDD175 increased K(+) currents in a dose-dependent manner, and washout of LDD175 or the addition of iberiotoxin fully reversed the increase. Intravenous LDD175 improved erectile function measured by area under the curve (AUC) of the intracavernosal pressure (ICP)/arterial blood pressure (ABP) ratio (1,612.1 ± 135.6 vs. 1,093.7 ± 123.1, P < 0.05). There was no difference between 10 mg/kg LDD175 and 1 mg/kg udenafil regarding maximal ICP, maximal ICP/ABP ratio, and the AUC of the ICP/ABP ratio (P > 0.05).

CONCLUSIONS

LDD175 leads to an endothelium-independent relaxation of erectile tissue, primarily through the opening of BKCa channels. The results suggest that LDD175 might be a new candidate treatment for erectile dysfunction.

Effects of Korean ginseng berry extract (GB0710) on penile erection: evidence from in vitro and in vivo studies

Several reports have promoted the root-derived Korean red ginseng (KRG; Panax ginseng) as alternative treatment for erectile dysfunction (ED), and ginsenosides are known to be the principal active ingredients of ginseng. Recent studies showed that ginseng berries produce more ginsenosides than KRG; thus, we investigated the ability of the Korean ginseng berry extract GB0710 to relax the penile corpus cavernosum smooth muscle (CCSM) in this study. As a comparative control, the results were compared to those obtained using KRG. In addition, possible mechanisms of action for GB0710 were investigated. While KRG and GB0710 both displayed dose-dependent relaxation effects on precontracted rabbit CCSM in vitro, GB0710 was shown to be more potent than KRG. The GB0710-induced relaxation could be partially reduced by removing the endothelium. In addition, pre-treatment with several nitric oxide (NO) inhibitors significantly inhibited the relaxation of muscle strips. Furthermore, administration of GB0710 increased intracavernosal pressure (ICP) in a rat in vivo model in both a dose- and duration-dependent manner. Intracellular NO production in human microvascular endothelial cells could be induced by GB0710 and inhibited by N(G)-monomethyl-L-arginine. In conclusion, GB0710 had a greater relaxation effect on rabbit CCSM than did KRG extract, and increased ICP in a rat model in both a dose- and a duration-dependent manner. This relaxing effect might be mediated by NO production.

Effects of Korean ginseng berry extract on sexual function in men with erectile dysfunction: a multicenter, placebo-controlled, double-blind clinical study

Ginseng is beneficial for many aspects of human physiology, including sexual function. In this study, we have evaluated the efficacy and safety of an extract of ginseng berry, which has a ginsenoside profile distinct from other parts of the plant, on sexual function in men with erectile dysfunction. In all, 119 men with mild-to-moderate ED participated in a multicenter, randomized, double-blind, parallel, placebo-controlled clinical study. They were administered 4 tablets of either standardized Korean ginseng berry (SKGB, 350 mg ginseng berry extract per tablet), or placebo, daily, for 8 weeks. Efficacy was assessed with the International Index of Erectile Function (IIEF)-15 and premature ejaculation diagnostic tool (PEDT) at the end of the 4th and 8th week. We observed that the total and each of the individual domain scores of IIEF-15 increased from 40.95 ± 7.05 to 46.19 ± 12.69 significantly in the SKGB by the 8th week (P<0.05). The erectile function domain of IIEF changed slightly from 17.17 ± 2.57 to 18.59 ± 5.99 in the SKGB group by the 8th week (P<0.05). In addition, PEDT scores significantly improved from 9.14 ± 4.57 to 7.97 ± 4.4 and 7.53 ± 4.26 in the SKGB group after 4 and 8 weeks of treatment (P<0.05). Safety markers including hormone and lipid in the blood were assessed at the end of the 4th and 8th week and they remained unchanged. Oral administration of the SKGB extract improved all domains of sexual function. It can be used as an alternative medicine to improve sexual life in men with sexual dysfunction.