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Bladder response to urethral flow in the awake ewe.
G Robain1, H Combrisson, L Mazières
1Department of Rehabilitation, Hôpital Jean Rostand, Ivry/Seine, France. gilberte.robain@jrs.ap-hop-paris.fr
Neurourology and Urodynamics
|September 28, 2001
Summary
Urethral flow triggers bladder contractions in awake animals, a reflex crucial for complete bladder emptying. This finding suggests descending inhibitory controls, not absent pathways, explain why this reflex is hard to see in humans.
Area of Science:
- Urology
- Neuroscience
- Physiology
Background:
- Urethral flow can stimulate bladder micturition contractions, aiding complete bladder emptying.
- This reflex is documented in animals but difficult to observe in awake humans.
Purpose of the Study:
- To investigate the urethral flow-evoked micturition reflex in awake, intact ewes using urodynamics.
- To understand the physiological basis of this reflex in a conscious state.
Main Methods:
- Awake ewes were instrumented for urodynamic measurements, including bladder and rectal pressure.
- Urethral flows were induced by saline injection into the proximal urethra.
- Responses to flow were assessed at varying bladder volumes.
Main Results:
- Urethral flows consistently elicited detrusor contractions in all ewes.
- The reflex response initiated within 2 seconds, outlasted the stimulus, and required bladder filling.
- Local anesthesia of urethral mucosa abolished the reflex, confirming urethral receptor involvement.
Conclusions:
- Small urethral flows induce significant bladder micturition contractions in awake animals.
- This reflex is likely important in normal micturition and may be inhibited in humans by descending controls.