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Contribution of the external urethral sphincter to urinary void size in unanesthetized unrestrained rats
Author(s) -
LaPallo Brandon K.,
Wolpaw Jonathan R.,
Chen Xiang Yang,
Carp Jonathan S.
Publication year - 2016
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.22789
Subject(s) - bursting , medicine , electrophysiology , urethral sphincter , urination , urinary system , anesthesia , anatomy , urethra , neuroscience , biology
Aims In anesthetized rats, voiding is typically associated with phasic activation (bursting) of the external urethral sphincter (EUS). During spontaneous voiding in unanesthetized, unrestrained rats, EUS bursting is the most common form of EUS activity exhibited, but it is not necessary for productive voiding to occur. The aim of the present study was to determine which aspects of EUS activity contributed to void size during bursting and non‐bursting voiding in conscious, freely moving rats. Methods Female rats were implanted with electrodes adjacent to the EUS for recording electromyographic activity (EMG). EUS EMG recordings were performed during 24‐hr sessions in a metabolic cage while voided urine was continuously collected and weighed. Results Void size was positively correlated with the duration of the intra‐burst silent and active periods and variables reflecting the overall intensity and duration of bursting, particularly at lower frequencies within the 3‐10 Hz range of EUS bursting. In addition, void size was inversely related to the frequency of bursting and to the average EMG amplitude during voiding, both in voids with and without bursting. Conclusions EUS bursting contributes to productive voiding when bursting is present. Lower bursting frequencies elicit more productive voiding than do higher frequencies. In the absence of bursting, the association of increased void size with smaller average EUS EMG amplitude suggests that conscious rats can perform synergic voiding (i.e., bladder contraction with EUS relaxation) that is comparable to that seen in humans and other typically non‐bursting species. Neurourol. Urodynam. 35:696–702, 2016 . © 2015 Wiley Periodicals, Inc.