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An exploration of the control of micturition using a novel in situ arterially perfused rat preparation.

Sadananda P, Drake MJ, Paton JF, Pickering AE - Front Neurosci (2011)

Bottom Line: Our goal was to develop and refine a decerebrate arterially perfused rat (DAPR) preparation that allows the complete bladder filling and voiding cycle to be investigated without some of the restrictions inherent with in vivo experimentation [e.g., ease and speed of set up (30 min), control over the extracellular milieu and free of anesthetic agents].The DAPR allows the simultaneous measurement of bladder intra-luminal pressure, external urinary sphincter-electromyogram (EUS-EMG), pelvic afferent nerve activity, pudendal motor activity, and permits excellent visualization of the entire lower urinary tract, during typical rat filling and voiding responses.Both innocuous (e.g., perineal stimulation) and nociceptive (tail/paw pinch) somatic stimuli elicited an increase in EUS-EMG indicating intact sensory feedback loops.

View Article: PubMed Central - PubMed

Affiliation: School of Physiology and Pharmacology, University of Bristol Bristol, UK.

ABSTRACT
Our goal was to develop and refine a decerebrate arterially perfused rat (DAPR) preparation that allows the complete bladder filling and voiding cycle to be investigated without some of the restrictions inherent with in vivo experimentation [e.g., ease and speed of set up (30 min), control over the extracellular milieu and free of anesthetic agents]. Both spontaneous (naturalistic bladder filling from ureters) and evoked (in response to intravesical infusion) voids were routinely and reproducibly observed which had similar pressure characteristics. The DAPR allows the simultaneous measurement of bladder intra-luminal pressure, external urinary sphincter-electromyogram (EUS-EMG), pelvic afferent nerve activity, pudendal motor activity, and permits excellent visualization of the entire lower urinary tract, during typical rat filling and voiding responses. The voiding responses were modulated or eliminated by interventions at a number of levels including at the afferent terminal fields (intravesical capsaicin sensitization-desensitization), autonomic (ganglion blockade with hexamethonium), and somatic motor (vecuronium block of the EUS) outflow and required intact brainstem/hindbrain-spinal coordination (as demonstrated by sequential hindbrain transections). Both innocuous (e.g., perineal stimulation) and nociceptive (tail/paw pinch) somatic stimuli elicited an increase in EUS-EMG indicating intact sensory feedback loops. Spontaneous non-micturition contractions were observed between fluid infusions at a frequency and amplitude of 1.4 ± 0.9 per minute and 1.4 ± 0.3 mmHg, respectively and their amplitude increased when autonomic control was compromised. In conclusion, the DAPR is a tractable and useful model for the study of neural bladder control showing intact afferent signaling, spinal and hindbrain co-ordination and efferent control over the lower urinary tract end organs and can be extended to study bladder pathologies and trial novel treatments.

No MeSH data available.


Related in: MedlinePlus

Rate of fluid infusion and bladder pressure at void. (A) Example voids showing that at slower infusion rates (e.g., 20 μl/min) it took longer for a void to be triggered and a larger number of NMCs were observed before the void. Note also the EMG activity that accompanied each NMC. At higher infusion rates, fewer NMCs occurred before the void. (B) The rate of fluid infusion did not significantly alter the bladder pressure at which the void occurred (C) A statistically significant linear relationship (P < 0.0001; R2 = 0.83; n = 4) was observed between infusion rate and the volume infused into the bladder before voiding was triggered.
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Figure 4: Rate of fluid infusion and bladder pressure at void. (A) Example voids showing that at slower infusion rates (e.g., 20 μl/min) it took longer for a void to be triggered and a larger number of NMCs were observed before the void. Note also the EMG activity that accompanied each NMC. At higher infusion rates, fewer NMCs occurred before the void. (B) The rate of fluid infusion did not significantly alter the bladder pressure at which the void occurred (C) A statistically significant linear relationship (P < 0.0001; R2 = 0.83; n = 4) was observed between infusion rate and the volume infused into the bladder before voiding was triggered.

Mentions: Variable urine infusion rates (from 10 to 110 μl per minute) were used to examine the characteristics of the filling/voiding response (n = 4). As expected at low infusion rates (10–20 μl/min) it took longer before a void was triggered. These slow fills were also associated with more NMCs, which were accompanied with synchronous tonic EUS–EMG activity (Figure 4A). The bladder pressure at which voiding occurred was independent of infusion rates (26.6 ± 0.3 mmHg; n = 14, Figure 4B). However, at higher infusion rates a greater volume of fluid was administered into the bladder before voiding was triggered (P < 0.0001; Figure 4C).


An exploration of the control of micturition using a novel in situ arterially perfused rat preparation.

Sadananda P, Drake MJ, Paton JF, Pickering AE - Front Neurosci (2011)

Rate of fluid infusion and bladder pressure at void. (A) Example voids showing that at slower infusion rates (e.g., 20 μl/min) it took longer for a void to be triggered and a larger number of NMCs were observed before the void. Note also the EMG activity that accompanied each NMC. At higher infusion rates, fewer NMCs occurred before the void. (B) The rate of fluid infusion did not significantly alter the bladder pressure at which the void occurred (C) A statistically significant linear relationship (P < 0.0001; R2 = 0.83; n = 4) was observed between infusion rate and the volume infused into the bladder before voiding was triggered.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3097374&req=5

Figure 4: Rate of fluid infusion and bladder pressure at void. (A) Example voids showing that at slower infusion rates (e.g., 20 μl/min) it took longer for a void to be triggered and a larger number of NMCs were observed before the void. Note also the EMG activity that accompanied each NMC. At higher infusion rates, fewer NMCs occurred before the void. (B) The rate of fluid infusion did not significantly alter the bladder pressure at which the void occurred (C) A statistically significant linear relationship (P < 0.0001; R2 = 0.83; n = 4) was observed between infusion rate and the volume infused into the bladder before voiding was triggered.
Mentions: Variable urine infusion rates (from 10 to 110 μl per minute) were used to examine the characteristics of the filling/voiding response (n = 4). As expected at low infusion rates (10–20 μl/min) it took longer before a void was triggered. These slow fills were also associated with more NMCs, which were accompanied with synchronous tonic EUS–EMG activity (Figure 4A). The bladder pressure at which voiding occurred was independent of infusion rates (26.6 ± 0.3 mmHg; n = 14, Figure 4B). However, at higher infusion rates a greater volume of fluid was administered into the bladder before voiding was triggered (P < 0.0001; Figure 4C).

Bottom Line: Our goal was to develop and refine a decerebrate arterially perfused rat (DAPR) preparation that allows the complete bladder filling and voiding cycle to be investigated without some of the restrictions inherent with in vivo experimentation [e.g., ease and speed of set up (30 min), control over the extracellular milieu and free of anesthetic agents].The DAPR allows the simultaneous measurement of bladder intra-luminal pressure, external urinary sphincter-electromyogram (EUS-EMG), pelvic afferent nerve activity, pudendal motor activity, and permits excellent visualization of the entire lower urinary tract, during typical rat filling and voiding responses.Both innocuous (e.g., perineal stimulation) and nociceptive (tail/paw pinch) somatic stimuli elicited an increase in EUS-EMG indicating intact sensory feedback loops.

View Article: PubMed Central - PubMed

Affiliation: School of Physiology and Pharmacology, University of Bristol Bristol, UK.

ABSTRACT
Our goal was to develop and refine a decerebrate arterially perfused rat (DAPR) preparation that allows the complete bladder filling and voiding cycle to be investigated without some of the restrictions inherent with in vivo experimentation [e.g., ease and speed of set up (30 min), control over the extracellular milieu and free of anesthetic agents]. Both spontaneous (naturalistic bladder filling from ureters) and evoked (in response to intravesical infusion) voids were routinely and reproducibly observed which had similar pressure characteristics. The DAPR allows the simultaneous measurement of bladder intra-luminal pressure, external urinary sphincter-electromyogram (EUS-EMG), pelvic afferent nerve activity, pudendal motor activity, and permits excellent visualization of the entire lower urinary tract, during typical rat filling and voiding responses. The voiding responses were modulated or eliminated by interventions at a number of levels including at the afferent terminal fields (intravesical capsaicin sensitization-desensitization), autonomic (ganglion blockade with hexamethonium), and somatic motor (vecuronium block of the EUS) outflow and required intact brainstem/hindbrain-spinal coordination (as demonstrated by sequential hindbrain transections). Both innocuous (e.g., perineal stimulation) and nociceptive (tail/paw pinch) somatic stimuli elicited an increase in EUS-EMG indicating intact sensory feedback loops. Spontaneous non-micturition contractions were observed between fluid infusions at a frequency and amplitude of 1.4 ± 0.9 per minute and 1.4 ± 0.3 mmHg, respectively and their amplitude increased when autonomic control was compromised. In conclusion, the DAPR is a tractable and useful model for the study of neural bladder control showing intact afferent signaling, spinal and hindbrain co-ordination and efferent control over the lower urinary tract end organs and can be extended to study bladder pathologies and trial novel treatments.

No MeSH data available.


Related in: MedlinePlus