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Updated: May 18, 2026
06:36
A Decentralized (Ex Vivo) Murine Bladder Model with the Detrusor Muscle Removed for Direct Access to the Suburothelium during Bladder Filling
Published on: November 28, 2019
Elevated steady-state bladder preload activates myosin phosphorylation: detrusor smooth muscle is a preload tension
Jordan B Southern1, Jasmine R Frazier, Amy S Miner
1Virginia Commonwealth Univ. School of Medicine, Depts. of Biochemistry and Molecular Biology and Pediatrics, Richmond, VA 23298-0614, USA.
American Journal of Physiology. Renal Physiology
|September 21, 2012
Summary
Rabbit bladder detrusor muscle exhibits filling tone dependent on preload tension, not muscle length. This suggests detrusor muscle acts as a preload sensor, offering potential therapeutic targets for bladder contractile disorders like overactive bladder.
Area of Science:
- Urology
- Physiology
- Muscle Biology
Background:
- Bladder filling tone results from adjustable preload and autonomous contractile tensions.
- Understanding detrusor muscle length-dependent tone is crucial for bladder function.
- Neuronal mechanosensors linked to urgency are in series with detrusor muscle.
Purpose of the Study:
- To investigate if detrusor muscle filling tone depends on muscle length.
- To differentiate contributions of preload tension and autonomous contraction to filling tone.
- To explore detrusor muscle's role as a preload sensor.
Main Methods:
- Measured maximum active tension induced by KCl at varying muscle lengths (70%-120% L(ref)).
- Assessed filling tone with and without ibuprofen (to block autonomous contraction).
- Evaluated tone during PGE(2)-induced contractions and measured myosin phosphorylation.
Main Results:
- Maximum KCl-induced tension showed a parabolic length-tension relationship.
- Filling tone increased linearly with muscle length from 70% to 120% L(ref).
- Adjustable preload tension, but not autonomous contraction, was linearly dependent on length; detrusor muscle demonstrated length-hysteresis, sensing preload.
Conclusions:
- Detrusor muscle filling tone is primarily dependent on adjustable preload tension, which increases linearly with stretch.
- The detrusor muscle functions as a preload tension sensor, not a length sensor.
- This finding may identify novel therapeutic targets for overactive bladder and other contractile disorders.
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