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Urethral responses to sacral stimulation in chronic spinal dog
J S Walter1, J S Wheeler, C J Robinson
1Hines Veterans Affairs Hospital, Rehabilitation Research and Development Center 60141.
The American Journal of Physiology
|August 1, 1989
Summary
Investigating urethral activity in spinal-injured canines revealed that the rhabdosphincter plays a key role in voiding patterns following sacral stimulation. This finding offers insights into bladder control after spinal cord injury.
Area of Science:
- Neuroscience
- Urology
- Veterinary Medicine
Background:
- Spinal cord injury (SCI) often leads to significant bladder dysfunction.
- Understanding the mechanisms of voiding in chronic SCI is crucial for developing effective treatments.
- The role of urethral activity, particularly the rhabdosphincter, in post-SCI voiding patterns requires further elucidation.
Purpose of the Study:
- To investigate urethral activity and voiding patterns in awake, chronic spinal-injured canines.
- To determine the involvement of the membranous urethra and rhabdosphincter in voiding responses to sacral stimulation.
Main Methods:
- Urodynamic recordings, video cystofluoroscopy, and urethral pressure recordings were utilized in awake, chronic spinal-injured canines.
- Bladder contractions and voiding were induced via electrical stimulation using epidural electrodes in the sacral canal.
- Voiding patterns were observed and analyzed during and after stimulation.
Main Results:
- Urethral pressure remained elevated during and briefly after sacral electrical stimulation.
- Three distinct poststimulation voiding patterns were identified: pulsatile, 'on and off', and steady-stream.
- Fluoroscopic analysis indicated the proximal membranous urethra's critical role in all observed voiding patterns.
Conclusions:
- The skeletal muscle of the membranous urethra (rhabdosphincter) is actively involved in voiding responses in chronic spinal-injured canines.
- Sacral stimulation influences urethral activity, contributing to diverse voiding patterns.
- These findings highlight the rhabdosphincter's importance in bladder voiding mechanisms following spinal cord injury.