Neurourology and Urodynamics 25:283^289 (2006) Impaired Micturition Re£ex Caused by Acute Selective Dorsal or Ventral Root(s) Rhizotomy in Anesthetized Rats Jiuan-Miaw Liao, 1 Chen-Li Cheng, 2 Shin-Da Lee, 3 Gin-Den Chen, 4 Kuo-Jung Chen, 1 Chao-Hsun Yang, 5 Shwu-Fen Pan, 6 Mei-Jung Chen, 7 Pei-Chen Huang, 8 and Tzer-Bin Lin 1 * 1 Department of Physiology, College of Medicine, Chung-Shan Medical University, Taichung, Taiwan 2 Department of Surgery, Division of Urology, Taichung Veterans General Hospital, Taichung, Taiwan 3 School of Physical Therapy, College of Medicine, Chung-Shan Medical University, Taichung, Taiwan 4 Department of Obstetrics and Gynecology, Hospital, Chung-Shan Medical University, Taichung, Taiwan 5 Department of Cosmetic Science, Providence University, Taichung, Taiwan 6 Department of Biotechnology, Ming-Chuan University, Taoyuan, Taiwan 7 Department of Applied Cosmetic, Ching-Kuo Institute of Management and Health, Keelong, Taiwan 8 School of Medicine, Kao-Hsiung Medical University, Kaohsiung, Taiwan Purpose: To clarify the contributions of parasympathetic inputs and outputs to the micturition re£ex. Materials and Methods: Intra-vesical pressure (IVP), external urethral sphincter electro- myogram (EMG), pelvic a¡erent nerve activities (PANA), and pelvic e¡erent nerve activities (PENA) as well as the time-derived IVP (dIVP, an index of bladder contractility) were evaluated in intact and acute dorsal or ventral root(s) rhizotomized (DRX and VRX, respectively) rats. Results: In DRX rats, when compared with that in intact stage, the voiding frequency was decreased (75  15% of intact, P < 0.05, n ¼ 8), while the threshold pressure to trigger voiding con- tractions was signi¢cantly increased (187  75% of intact, P < 0.05, n ¼ 8). In addition, several insu/cient contractions (5.3  3.5 contractions/voiding, P < 0.05, n ¼ 8) occurred in ahead of each voiding contraction. On the other hand, in VRX rats, the peak and rebound IVP were signi¢cantly decreased (90  3.5% and 75  11.3% of intact, P < 0.01, n ¼ 8), while the threshold pressure was not a¡ected (102  11% of intact, P ¼ NS, n ¼ 8). The time-derived parameters were signi¢cantly decreased in VRX (peak dIVP, 78  10.2%, rebound dIVP, 75  15.6%, minimal dIVP, 68  14% of intact, P < 0.01, n ¼ 8) but only peak dIVP was decreased (85  11% of intact, P < 0.01, n ¼ 8) in DRX rats. Conclusion: Acute selective DRX and VRX rat can be an animal model to investigate peripheral neural control in micturition functions. Neurourol. Urodynam. 25:283 ^289, 2006. ß 2006 Wiley-Liss, Inc. Key words: cystometry;electromyogram;motor;sensory;spinalcord INTRODUCTION Storage and voiding are the two main functions of the urinary bladder. In human beings, mechanoreceptors on the bladder wall generate action potentials that transmit centripe- tally onto the dorsal horn through the pelvic a¡erent nerve during storage. After integration within the spinal cord, motor impulses propagate through the pudendal e¡erent nerve and induce contraction in external urethral sphincter, therefore, result in continence [De Groat and Yoshimura, 2001]. On the other hand, once the a¡erent impulses are su/- cient to trigger a voiding contraction, a long spinobulbospinal arc, providing an excitatory out£ow to the detrusor as well as an inhibitory out£ow to the urethral sphincter muscle, is acti- vated to induce voiding [Brading and Williams, 1990; Chien et al., 2000]. Di¡erent from human beings, some animal, such as dogs and rats, exhibit activities in external urethral sphincter, which contribute to urethral pumping activity needed for su/cient urine elimination in these species [Kakizaki et al., 2001 ]. Micturition function is disturbed in patients with damages to descending controls form higher neurological centers or to the re£ex circuitry itself [Mallory et al., 1991; Ishiura et al., 2001]. Restoration of voiding func- tion in patients with neurological de¢cits is a challenge in This paper was received, reviewed, and accepted by the previous editorial board under the leadership of the past editor, Dr. Jerry Blaivas. Grant sponsor: National Science Council of the Republic of China; Grant numbers: NSC 92-2320-B-040-036, NSC 93-2320-B-040-065, NSC 94-2320- B-040-026. *Correspondence to: Dr. Tzer-Bin Lin, Department of Physiology, College of Medicine, Chung-Shan Medical University, No. 110, Chang-Kuo North Rd., the ¢rst Section,Taichung,Taiwan 40201. E-mail: tblin@csmu.edu.tw Received 12 July 2005; Accepted 6 December 2005 Published online 22 February 2006 inWiley InterScience (www.interscience.wiley.com) DOI 10.1002/nau.20220 ß 2006Wiley-Liss,Inc.