1. Department of Obstetrics and Gynecology, Chungbuk National University College of Medicine, Cheongju 28644, Korea.
2. Department Physiology, Chungbuk National University College of Medicine, Cheongju 28644, Korea.
3. Department of Pharmacology, Chungbuk National University College of Medicine, Cheongju 28644, Korea.
4. Department of Urology, College of Medicine, Chung-Ang University, Seoul 06974, Korea.
5. Department of Physiology, College of Medicine, Chung-Ang University, Seoul 06974, Korea.
6. VHS Medical Center, Seoul 05368, Korea.
7. Department of Physiology, Nagoya City University Medical School, Nagoya 467-8601, Japan.
8. Department of Obstetrics and Gynecology, Cheongju St. Mary's Hospital, Cheongju 28323, Korea.
9. Department of Preventive Medicine, Chungbuk National University College of Medicine, Cheongju 28644, Korea.
10. Department of Physiology, Shanghai Jiaotong University, School of Medicine, Shanghai, 200240, P.R. China.
11. Department of Medical Education, Chungbuk National University College of Medicine, Cheongju 28644, Korea.