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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

Linear relationship between afferent activity and bladder pressure. A linear polynomial fit of afferent nerve activity as a function of bladder pressure recorded during the relaxation phase of a voiding contraction in the same rat after saline (upper panel) and acetic acid (lower panel) filling. Dots represent the measured afferent activity and the solid line represents the fitted model
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Fig4: Linear relationship between afferent activity and bladder pressure. A linear polynomial fit of afferent nerve activity as a function of bladder pressure recorded during the relaxation phase of a voiding contraction in the same rat after saline (upper panel) and acetic acid (lower panel) filling. Dots represent the measured afferent activity and the solid line represents the fitted model

Mentions: In the post-void relaxation phase, the time constant of exponential pressure decay (τ) in the interval t2 − tbaseline was not significantly different between AA and saline measurements. The average afferent activity, the maximum afferent activity and the mean value of the normalized slope in the interval t2 − tbaseline were significantly higher in AA than in saline measurements, whereas the mean value of pressure (t2 − tbaseline) was found to be higher in saline measurements. The baseline afferent activity and baseline pressure (pbaseline) after the voiding contraction did not differ significantly (Table 2). The correlation coefficient (Pearson’s product-moment correlation), which is a measure of the linear dependence of nerve activity on bladder pressure, was significantly higher in AA (Table 2), whereas the SNR and the goodness of fit (R2), which describes how well the model fitted the data, did not differ significantly. An example of a fitted line in a saline and an AA measurement is shown in Fig. 4.Fig. 4


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)

Linear relationship between afferent activity and bladder pressure. A linear polynomial fit of afferent nerve activity as a function of bladder pressure recorded during the relaxation phase of a voiding contraction in the same rat after saline (upper panel) and acetic acid (lower panel) filling. Dots represent the measured afferent activity and the solid line represents the fitted model
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

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

Fig4: Linear relationship between afferent activity and bladder pressure. A linear polynomial fit of afferent nerve activity as a function of bladder pressure recorded during the relaxation phase of a voiding contraction in the same rat after saline (upper panel) and acetic acid (lower panel) filling. Dots represent the measured afferent activity and the solid line represents the fitted model
Mentions: In the post-void relaxation phase, the time constant of exponential pressure decay (τ) in the interval t2 − tbaseline was not significantly different between AA and saline measurements. The average afferent activity, the maximum afferent activity and the mean value of the normalized slope in the interval t2 − tbaseline were significantly higher in AA than in saline measurements, whereas the mean value of pressure (t2 − tbaseline) was found to be higher in saline measurements. The baseline afferent activity and baseline pressure (pbaseline) after the voiding contraction did not differ significantly (Table 2). The correlation coefficient (Pearson’s product-moment correlation), which is a measure of the linear dependence of nerve activity on bladder pressure, was significantly higher in AA (Table 2), whereas the SNR and the goodness of fit (R2), which describes how well the model fitted the data, did not differ significantly. An example of a fitted line in a saline and an AA measurement is shown in Fig. 4.Fig. 4

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