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Neurophysiological modeling of bladder afferent activity in the rat overactive bladder model.

Choudhary M, van Asselt E, van Mastrigt R, Clavica F - J Physiol Sci (2015)

Bottom Line: The afferent activity in the filling phase and the slope, i.e., the sensitivity of the afferent fibers to pressure changes in the post-void relaxation phase, were found to be significantly higher in AA than in saline measurements, while the offset (nerve activity at pressure ~0) and maximum pressure were comparable.We have thus shown, for the first time, that the sensitivity of afferent fibers in the OAB can be studied without cutting nerves or preparation of single fibers.We conclude that bladder overactivity induced by AA in rats is neurogenic in origin and is caused by increased sensitivity of afferent sensors in the bladder wall.

View Article: PubMed Central - PubMed

Affiliation: Department of Urology, Sector FURORE, Erasmus MC, Room EE1630, Dr. Molewaterplein 50, 3015 GE, Rotterdam, The Netherlands, m.choudhary@erasmusmc.nl.

ABSTRACT
The overactive bladder (OAB) is a syndrome-based urinary dysfunction characterized by "urgency, with or without urge incontinence, usually with frequency and nocturia". Earlier we developed a mathematical model of bladder nerve activity during voiding in anesthetized rats and found that the nerve activity in the relaxation phase of voiding contractions was all afferent. In the present study, we applied this mathematical model to an acetic acid (AA) rat model of bladder overactivity to study the sensitivity of afferent fibers in intact nerves to bladder pressure and volume changes. The afferent activity in the filling phase and the slope, i.e., the sensitivity of the afferent fibers to pressure changes in the post-void relaxation phase, were found to be significantly higher in AA than in saline measurements, while the offset (nerve activity at pressure ~0) and maximum pressure were comparable. We have thus shown, for the first time, that the sensitivity of afferent fibers in the OAB can be studied without cutting nerves or preparation of single fibers. We conclude that bladder overactivity induced by AA in rats is neurogenic in origin and is caused by increased sensitivity of afferent sensors in the bladder wall.

No MeSH data available.


Related in: MedlinePlus

Experimental set-up. After exposing the abdominal cavity, a 23G needle was inserted at the top of the bladder for filling and pressure measurement. The other end of the needle was attached to a disposable pressure transducer and an infusion pump using a 2-way connector. Custom-made bipolar electrodes consisting of two thin platinum–iridium hook shaped wires separated by a distance of 0.5–1 mm were placed under one of the branches of the pelvic nerve using a micromanipulator. The recorded nerve signal was then amplified and band pass filtered
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Fig1: Experimental set-up. After exposing the abdominal cavity, a 23G needle was inserted at the top of the bladder for filling and pressure measurement. The other end of the needle was attached to a disposable pressure transducer and an infusion pump using a 2-way connector. Custom-made bipolar electrodes consisting of two thin platinum–iridium hook shaped wires separated by a distance of 0.5–1 mm were placed under one of the branches of the pelvic nerve using a micromanipulator. The recorded nerve signal was then amplified and band pass filtered

Mentions: After the surgical procedures, the saline was removed and the pelvic cavity was kept moist by warm paraffin oil throughout the electrophysiological measurements. Bladder pressure measurement and bladder filling (0.05 ml/min) were done by inserting a 23G needle at the top of the bladder. The other end of the needle was attached to a disposable pressure transducer and an infusion pump using a 2-way connector. Pressure was measured using a Statham SPI400 blood pressure monitor. The bladder was repeatedly filled with saline or 0.5 % AA until a voiding contraction occurred or for a maximum duration of 20 min (up to ~1 ml), whichever happened first. Custom-made bipolar electrodes consisting of two thin (diameter 0.1 mm) platinum-iridium hook-shaped wires separated by a distance of 0.5–1 mm were used for the nerve signal recordings. The electrode was mounted on a micromanipulator and one of the identified nerves was carefully placed on the wires. A brief illustration of the experimental set-up is shown in Fig. 1. In 4 of the 18 rats, a left side postganglionic pelvic nerve branch was crushed between the major pelvic ganglion and the electrode, to eliminate efferent nerve signals and record afferent activity only. The pressure transducer was calibrated using a column of water before the start of each experiment. The nerve signal was calibrated using a 1-µV (500 Hz) sinusoidal test signal. The rats were euthanized at the end of the experiment with an overdose of KCl, injected into the heart.Fig. 1


Neurophysiological modeling of bladder afferent activity in the rat overactive bladder model.

Choudhary M, van Asselt E, van Mastrigt R, Clavica F - J Physiol Sci (2015)

Experimental set-up. After exposing the abdominal cavity, a 23G needle was inserted at the top of the bladder for filling and pressure measurement. The other end of the needle was attached to a disposable pressure transducer and an infusion pump using a 2-way connector. Custom-made bipolar electrodes consisting of two thin platinum–iridium hook shaped wires separated by a distance of 0.5–1 mm were placed under one of the branches of the pelvic nerve using a micromanipulator. The recorded nerve signal was then amplified and band pass filtered
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4477068&req=5

Fig1: Experimental set-up. After exposing the abdominal cavity, a 23G needle was inserted at the top of the bladder for filling and pressure measurement. The other end of the needle was attached to a disposable pressure transducer and an infusion pump using a 2-way connector. Custom-made bipolar electrodes consisting of two thin platinum–iridium hook shaped wires separated by a distance of 0.5–1 mm were placed under one of the branches of the pelvic nerve using a micromanipulator. The recorded nerve signal was then amplified and band pass filtered
Mentions: After the surgical procedures, the saline was removed and the pelvic cavity was kept moist by warm paraffin oil throughout the electrophysiological measurements. Bladder pressure measurement and bladder filling (0.05 ml/min) were done by inserting a 23G needle at the top of the bladder. The other end of the needle was attached to a disposable pressure transducer and an infusion pump using a 2-way connector. Pressure was measured using a Statham SPI400 blood pressure monitor. The bladder was repeatedly filled with saline or 0.5 % AA until a voiding contraction occurred or for a maximum duration of 20 min (up to ~1 ml), whichever happened first. Custom-made bipolar electrodes consisting of two thin (diameter 0.1 mm) platinum-iridium hook-shaped wires separated by a distance of 0.5–1 mm were used for the nerve signal recordings. The electrode was mounted on a micromanipulator and one of the identified nerves was carefully placed on the wires. A brief illustration of the experimental set-up is shown in Fig. 1. In 4 of the 18 rats, a left side postganglionic pelvic nerve branch was crushed between the major pelvic ganglion and the electrode, to eliminate efferent nerve signals and record afferent activity only. The pressure transducer was calibrated using a column of water before the start of each experiment. The nerve signal was calibrated using a 1-µV (500 Hz) sinusoidal test signal. The rats were euthanized at the end of the experiment with an overdose of KCl, injected into the heart.Fig. 1

Bottom Line: The afferent activity in the filling phase and the slope, i.e., the sensitivity of the afferent fibers to pressure changes in the post-void relaxation phase, were found to be significantly higher in AA than in saline measurements, while the offset (nerve activity at pressure ~0) and maximum pressure were comparable.We have thus shown, for the first time, that the sensitivity of afferent fibers in the OAB can be studied without cutting nerves or preparation of single fibers.We conclude that bladder overactivity induced by AA in rats is neurogenic in origin and is caused by increased sensitivity of afferent sensors in the bladder wall.

View Article: PubMed Central - PubMed

Affiliation: Department of Urology, Sector FURORE, Erasmus MC, Room EE1630, Dr. Molewaterplein 50, 3015 GE, Rotterdam, The Netherlands, m.choudhary@erasmusmc.nl.

ABSTRACT
The overactive bladder (OAB) is a syndrome-based urinary dysfunction characterized by "urgency, with or without urge incontinence, usually with frequency and nocturia". Earlier we developed a mathematical model of bladder nerve activity during voiding in anesthetized rats and found that the nerve activity in the relaxation phase of voiding contractions was all afferent. In the present study, we applied this mathematical model to an acetic acid (AA) rat model of bladder overactivity to study the sensitivity of afferent fibers in intact nerves to bladder pressure and volume changes. The afferent activity in the filling phase and the slope, i.e., the sensitivity of the afferent fibers to pressure changes in the post-void relaxation phase, were found to be significantly higher in AA than in saline measurements, while the offset (nerve activity at pressure ~0) and maximum pressure were comparable. We have thus shown, for the first time, that the sensitivity of afferent fibers in the OAB can be studied without cutting nerves or preparation of single fibers. We conclude that bladder overactivity induced by AA in rats is neurogenic in origin and is caused by increased sensitivity of afferent sensors in the bladder wall.

No MeSH data available.


Related in: MedlinePlus