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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

Nerve activity and bladder pressure during a voiding cycle. An example of a pressure-afferent nerve activity measurement with saline and AA filling in the same rat. The bladder filling started at t = 0. The upper panel of both a and b shows the pressure during filling phase and a typical rat voiding contraction. The lower panel of a and b shows the nerve activity
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Fig3: Nerve activity and bladder pressure during a voiding cycle. An example of a pressure-afferent nerve activity measurement with saline and AA filling in the same rat. The bladder filling started at t = 0. The upper panel of both a and b shows the pressure during filling phase and a typical rat voiding contraction. The lower panel of a and b shows the nerve activity

Mentions: Postganglionic bladder nerve activity and bladder pressure were successfully measured in 10 out of 14 rats. A total of 84 measurements were recorded from these 10 rats (Table 1): 28 measurements were excluded because of artifacts, as described in the preceding section. The remaining 56 measurements had a SNR >0.5, i.e., the nerve activity was ≥50 % higher than baseline activity. For the analysis of the filling phase, an additional 21 measurements were excluded because of artifacts and parameters were calculated for 35 measurements (saline = 15, AA = 20). Figure 3 shows an example of a good pressure-nerve activity recording with saline and AA filling from the same rat. The bladder filling started at t = 0 and was stopped at the beginning of a voiding contraction. After the voiding contraction, both in saline and AA, the pressure declined smoothly to baseline in a similar fashion. It can be noted that similar to pressure, the nerve activity also followed a smoothly declining pattern.Table 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)

Nerve activity and bladder pressure during a voiding cycle. An example of a pressure-afferent nerve activity measurement with saline and AA filling in the same rat. The bladder filling started at t = 0. The upper panel of both a and b shows the pressure during filling phase and a typical rat voiding contraction. The lower panel of a and b shows the nerve activity
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

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

Fig3: Nerve activity and bladder pressure during a voiding cycle. An example of a pressure-afferent nerve activity measurement with saline and AA filling in the same rat. The bladder filling started at t = 0. The upper panel of both a and b shows the pressure during filling phase and a typical rat voiding contraction. The lower panel of a and b shows the nerve activity
Mentions: Postganglionic bladder nerve activity and bladder pressure were successfully measured in 10 out of 14 rats. A total of 84 measurements were recorded from these 10 rats (Table 1): 28 measurements were excluded because of artifacts, as described in the preceding section. The remaining 56 measurements had a SNR >0.5, i.e., the nerve activity was ≥50 % higher than baseline activity. For the analysis of the filling phase, an additional 21 measurements were excluded because of artifacts and parameters were calculated for 35 measurements (saline = 15, AA = 20). Figure 3 shows an example of a good pressure-nerve activity recording with saline and AA filling from the same rat. The bladder filling started at t = 0 and was stopped at the beginning of a voiding contraction. After the voiding contraction, both in saline and AA, the pressure declined smoothly to baseline in a similar fashion. It can be noted that similar to pressure, the nerve activity also followed a smoothly declining pattern.Table 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