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Comparison of the urethral properties of the female guinea pig and rat
Author(s) -
Walters Richard David,
McMurray Gordon,
Brading Alison Frances
Publication year - 2006
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.20194
Subject(s) - urination , medicine , urethral sphincter , urethra , guinea pig , phenylephrine , carbachol , in vivo , isometric exercise , urinary bladder , anatomy , urology , anesthesia , urinary system , biology , blood pressure , stimulation , microbiology and biotechnology
Aims The main focus of this study was to profile and compare urethral function in the female guinea pig and rat, and to characterize urodynamically distinctive patterns in the micturition cycle of the two species. This exercise aimed to investigate potential species‐related differences and determine a suitable animal model for the human urethra. Materials & Methods Female Dunkin–Hartley guinea pigs (400–500 g) and Sprague‐Dawley rats (200–300 g) were used throughout the study. For in vitro experiments urethral rings were suspended vertically for isometric tension recording in 5 ml organ baths and drugs (phenylephrine 10 −4 M and carbachol 10 −4 M) were applied directly to the bathing solution. In vivo urethral pull‐through and urodynamic studies were performed under urethane anesthesia, and phenylephrine (200 µg/kg) was administered during urethral pull‐through experiments via the intravenous (i.v.) route. Urethral, bladder and arterial pressures, and external urethral sphincter electromyographic (EMG) spike activity were recorded simultaneously throughout. Results Organ bath studies coupled with in vivo pull‐through experiments produced urethral profiles with distinct regional variations for both species. Urodynamic studies with the urethral probe fixed in the high pressure zones of the proximal urethra produced similar recordings in both species during bladder filling and marked differences during micturition. The guinea pig showed complete sphincteric inhibition immediately prior and during micturition as also seen in the human, whereas the rat exhibited high frequency bursts in EMG activity at this stage in the cycle. Conclusions The EMG activity seen in the rat during micturition is presumably necessary for efficient voiding, thus the guinea pig is a more suitable comparative model for the human in relation to urethral properties during micturition. Neurourol. Urodynam. © 2005 Wiley‐Liss, Inc.