Introduction The prevalence of erectile dysfunction (ED) and associated risk factors has been described in many countries, but there are still only a few studies from Asia. Aim We investigated the prevalences of ED and premature ejaculation (PE) in Korean men and the impact of general health, lifestyle, and psychosocial factors on these conditions. Methods To assess ED and PE, 1,570 Korean men aged 40–79 years were interviewed with a self-administered questionnaire on sexual function and the International Index of Erectile Function (IIEF)-5. In addition, blood chemistry was analyzed for each subject. Main Outcome Measures The prevalences of ED and PE were obtained from self-reported ED, IIEF-5 scoring, EF (erectile function) domain scoring, and self-reported intravaginal ejaculatory latency time (IELT). The data were analyzed for the presence of risk factors and the relationship of general health, lifestyle, and psychosocial factors with ED. Results The prevalences of ED among Korean men were 13.4% (self-reported ED) and 32.4% (IIEF-5 score ≤ 17), and PE prevalences were 11% (IELT ≤ 2-min) and 33.1% (IELT ≤ 5-min). ED was more prevalent in the subject groups with older age, lower income, or lower education, and in subjects without a spouse. ED prevalence was positively associated with risk factors such as diabetes, hypertension, heart disease, psychological stress, and obesity. Levels of serum hemoglobin (Hb) A1c, triglycerides, testosterone, or dehydroepiandrosterone sulfate (DHEA-S) were significantly different between the ED and non-ED groups. Conclusions The prevalences of ED and PE in Korean men were 13.4% (self-reported ED) and 11% (IELT ≤ 2-min), respectively. Risk factors and other socioeconomic and mental health factors were associated with ED prevalence. Biochemical factors such as HbA1c, triglycerides, testosterone, and DHEA-S were significantly related to ED prevalence.

In this pilot study in Korean men, those with BPH and treated with tadalafil 5 mg or tamsulosin 0.2 mg once daily experienced a reduction in LUTS, which was numerically (but not statistically) significant compared with the placebo. Tadalafil was well tolerated and few subjects discontinued the study due to treatment-emergent adverse events. Larger studies in Asian men with BPH and LUTS treated with phosphodiesterase type 5 inhibitors are needed.

We investigated the role of trabecular smooth muscle tone in regulation of intracavernosal pressure, venous outflow resistance, and penile capacitance. In an isolated rabbit whole penis model, corpora cavernosa were infused with either contracting (high K(+)-norepinephrine combination) or relaxing (no added Ca(2+)-papaverine combination) physiological salt solutions while intracavernosal pressure was recorded. An infusion pump regulated by an intracavernosal pressure feedback mechanism enabled the measurement of flow necessary to maintain intracavernosal pressures at 30, 60, 90, 120, and 150 mmHg under steady-state conditions (inflow = outflow). These experiments allowed resistance to outflow from corpora to be calculated when trabecular smooth muscle was either constricted or relaxed. Decay in intracavernosal pressure over time from various predetermined intracavernosal pressures (150, 120, 90, 60, and 30 mmHg) was studied under conditions of zero inflow following contraction or relaxation of trabecular smooth muscle. This permitted calculation of the time constant, which together with the outflow resistance, permitted the calculation of penile capacitance. When smooth muscle is relaxed, venous outflow resistance is high, constant, and independent of intracavernosal pressure. Furthermore, relaxation of smooth muscle allows expansion of corpora with accumulation of volume under pressure, enabling the penis to act as a capacitor. This capacitor function is limited in the presence of constant high outflow resistance by stiffness of the fibroelastic elements of penis, tunica, and fibroelastic frame, which exhibit nonlinear deflection trends. Analysis of these variables has led us to propose a model for penile erection.