Detrusor-sphincter dyssynergia induced by cold stimulation of the
urinary bladder of rats.
Cheng, Chen-Li, Chok-Yung Chai, and William C. De Groat.
Division of Urology, Department of Surgery, Taichung Veterans
General Hospital, Taichung, Taiwan, Republic of China, Division of
Urology, Department of Surgery, Tri-Service General Hospital,
National Defense Medical Center, and Department of Biomedical
Science, Academica Sinica, Taipei, Taiwan, Republic of China and
Department of Pharmacology, School of Medicine, University of
Pittsburgh, Pittsburgh, Pennsylvania 15261, U.S.A.
APStracts 3:0401R, 1996.
Instillation of cold water into the urinary bladder has been used as a
diagnostic test to evaluate neurogenic dysfunctions of the lower
urinary tract (LUT). This study examined the effects of cold
stimulation on the LUT of urethane anesthetized rats. Urinary bladder
pressure and external urethral sphincter electromyogram (EUS EMG)
were recorded during cystometrograms (CMGs) in which body or room
temperature saline was infused continuously into the bladder and
voided through the urethra. Subsequent infusion of cold saline (6
-8oC) into the bladder increased by approximately 100% the duration
and amplitude of supraspinal reflex bladder contractions, increased
baseline bladder pressure, increased the pressure threshold for
inducing micturition and increased EUS EMG activity. Blocking EUS
activity by transecting the pudendal nerves or by administering a
neuromuscular blocking agent markedly reduced or eliminated the
effect of cold stimulation. Capsaicin pretreatment suppressed the
effect of cold stimulation. It is concluded that cold temperatures
stimulate capsaicin-sensitive, C-fiber bladder afferents which
reflexly activate the EUS producing detrusor and sphincter
dyssynergia and increase urethral outlet resistance. This in turn
increases the amplitude and duration of bladder contractions during
voiding.
Received 16 August 1996; accepted in final form 4 November 1996.
APS Manuscript Number R496-6.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 31 December 1996