Reflex voiding in rat occurs at consistent bladder volume regardless of pressure or infusion rate

Study Purpose: This study was conducted to determine what state variables (bladder pressure or volume) the central nervous system uses to activate the micturition and guarding reflexes.

Data Collection: The activation of the micturition and guarding reflexes was observed during open outlet cystometry across many bladder infusion rates. For an individual animal, ten rates were sampled at least three times in a pseudorandom fashion. Infusion rates ranged from 0.92 to 65.5 ml/hr. Bladder pressure and external urethral sphincter electromyography (EUS EMG) were used to identify the onset of the micturition and guarding reflexes, respectively. Bladder volume was estimated from the measures of voided volume, residual volume, and infused volume.

Primary Conclusion: The micturition reflex was activated at constant volumes across many infusion rates, indicating that the central nervous system uses volume to activate the micturition reflex. The central nervous system may use bladder pressure to activate the guarding reflex.

Curator's Notes

Experimental Design: Rats were anesthetized using 1.2 g/kg urethane via subcutaneous injection. A catheter connected to a pressure transducer and computer-controlled infusion pump was inserted into the bladder dome. Silver electrode wires were percutaneously inserted into the external urethral sphincter for electromyography. Bladder capacity was estimated before data collection with 3-5 initial fill-to-void cycles. To cover a wide range of bladder sizes, some infusion rates were computed as a percentage of this initial capacity (relative rates), while others were predetermined and spanned different categories, including rates similar to ureter fluid addition, typical rates from previous rat cystometry studies, and extremely high rates. These infusion rates were used differently in various animal groups to maximize the overall rates tested. During the experiments, a set of 10 infusion rates, including relative and predefined rates, was randomly presented.

Completeness: This dataset is complete.

Subjects & Samples: Female (n = 25) adult Sprague-Dawley (RRID:RGD_10395233) rats were used in this study.

Primary vs derivative data: The primary data is structured with folders first organized by subject ID, followed by performance subfolders. Within each performance subfolder, you'll find LabChart recordings of bladder pressure, bladder volume, and electromyograms, all saved as MATLAB files. In the derivative data folder, you'll find summarized data for all subjects within a specific experimental group, saved as an Excel file. For more detailed information, please refer to the README file.