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Threshold for efferent bladder nerve firing in the rat
E van Asselt1, J le Feber, R van Mastrigt
1Department of Urology-Urodynamics, Erasmus University Rotterdam, 3000 DR Rotterdam, The Netherlands. vanasselt@udn.fgg.eur.nl
The American Journal of Physiology
|June 11, 1999
Summary
Voiding contractions are initiated by bladder afferent nerve activity reaching a threshold. Urethral afferent nerve activity does not trigger bladder contractions, as shown in anesthetized rats.
Area of Science:
- Urology
- Neuroscience
- Physiology
Background:
- The precise mechanism initiating the voiding reflex remains incompletely understood.
- Investigating neural control of bladder function is crucial for understanding lower urinary tract symptoms.
Purpose of the Study:
- To elucidate the neural mechanisms underlying the initiation of bladder contractions and voiding.
- To determine the role of bladder and urethral afferent nerve activity in triggering voiding.
Main Methods:
- Recording bladder pressure and bladder/urethral nerve activity in anesthetized rats.
- Utilizing a theoretical model to differentiate afferent and efferent bladder nerve activity.
- Defining the onset of bladder contraction based on efferent firing (t0).
Main Results:
- Bladder efferent firing initiated contractions at a bladder pressure of 1.0 +/- 0.4 kPa.
- Afferent bladder nerve activity at t0 was 2.0 +/- 0.6 microV, not exceeding previous levels.
- Urethral afferent nerve activity commenced at higher bladder pressures (2.1 +/- 1.1 kPa).
Conclusions:
- Urethral afferent nerve activity is unlikely to initiate bladder contractions.
- Voiding contractions are likely initiated by bladder afferent nerve activity surpassing a specific threshold.
- This study provides insight into the neural control of micturition.