Infusion pump for saline infusion

After recovering for 24 h, a CMG on fully awake and freely moving rats was conducted in a metabolic cage. The catheter was connected via a three‐way connector to an infusion pump for saline infusion (Braintree Scientific, Braintree, MA, USA), and a pressure transducer (Biopac Systems Inc., Santa Barbara, CA) for bladder pressure recording. Voiding responses were elicited by continuously infusing saline (0.9% NaCl) at a rate of 0.12 ml/min at room temperature (approximately 22°C). The same solution, temperature, and infusion rate were used in all three experiments. Urine was collected in a container coupled to a weight transducer (Biopac Systems Inc.). The cystometric evaluation was performed until 10 micturition cycles were recorded. After an additional 24 h, the same rats were anesthetized with 1.2 g/kg s.c. of urethane and a CMG test was once again performed. The CMG parameters analyzed included inter‐contraction interval, baseline bladder pressure, maximal bladder pressure, and voided volume.

After induction of anesthesia with urethane, the left ureter was catheterized, and the EUS‐EMG electrodes implanted (per above). The bladder catheter was then connected via a three‐way connector to an infusion pump for saline infusion (Braintree Scientific, Braintree, MA, USA) and a pressure transducer (World Precision Instruments [WPI, LLC]; Sarasota, FL, USA) for bladder pressure recording. The three EUS‐EMG electrodes were connected to a differential amplifier (A‐M Systems, Sequim, WA, USA). The animal was placed in a supine position on a surgical table in a reverse Trendelenburg position and a container coupled to a weight transducer (WPI, LLC) was placed under the rat for urine collection and measurement. Ten urination cycles were elicited with saline (rate: 0.12 ml/min). After the recording of 10 fill/void cycles, the abdominal wall was re‐opened and a flared PE‐60 catheter inserted into the bladder dome as described above, and the opening re‐closed. The ureter catheter was sealed and replaced with the dome catheter by connection to the pressure transducer and pump for the collection of 10 more fill‐void cycles. CMG parameters analyzed included baseline basal pressure, inter‐contraction interval, bursting period duration, void pressure, and maximal bladder pressure.