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Voiding reflex in chronic spinal cord injured cats induced by stimulating and blocking pudendal nerves
Author(s) -
Tai Changfeng,
Wang Jicheng,
Wang Xianchun,
Roppolo James R.,
de Groat William C.
Publication year - 2007
Publication title -
neurourology and urodynamics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.918
H-Index - 90
eISSN - 1520-6777
pISSN - 0733-2467
DOI - 10.1002/nau.20430
Subject(s) - medicine , pudendal nerve , reflex , anesthesia , cats , spinal cord , urination , urethral sphincter , stimulation , distension , anatomy , urology , surgery , urethra , urinary system , psychiatry
Aims To induce efficient voiding in chronic spinal cord injured (SCI) cats. Methods Voiding reflexes induced by bladder distension or by electrical stimulation and block of pudendal nerves were investigated in chronic SCI cats under α‐chloralose anesthesia. Results The voiding efficiency in chronic SCI cats induced by bladder distension was very poor compared to that in spinal intact cats (7.3 ± 0.9% vs. 93.6 ± 2.0%, P < 0.05). In chronic SCI cats continuous stimulation of the pudendal nerve on one side at 20 Hz induced large amplitude bladder contractions, but failed to induce voiding. However, continuous pudendal nerve stimulation (20 Hz) combined with high‐frequency (10 kHz) distal blockade of the ipsilateral pudendal nerve elicited efficient (73.2 ± 10.7%) voiding. Blocking the pudendal nerves bilaterally produced voiding efficiency (82.5 ± 4.8%) comparable to the efficiency during voidings induced by bladder distension in spinal intact cats, indicating that the external urethral sphincter (EUS) contraction was caused not only by direct activation of the pudendal efferent fibers, but also by spinal reflex activation of the EUS through the contralateral pudendal nerve. The maximal bladder pressure and average flow rate induced by stimulation and bilateral pudendal nerve block in chronic SCI cats were also comparable to those in spinal intact cats. Conclusions This study shows that after the spinal cord is chronically isolated from the pontine micturition center, bladder distension evokes a transient, inefficient voiding reflex, whereas stimulation of somatic afferent fibers evokes a strong, long duration, spinal bladder reflex that elicits efficient voiding when combined with blockade of somatic efferent fibers in the pudendal nerves. Neurourol. Urodynam. 26:879–886, 2007. © 2007 Wiley‐Liss, Inc.