Chronic urodynamic testing in conscious rats using an injection port coupled to a bladder catheter

Lower urinary tract (LUT) disorders are often causal factors for elderly enrollment in nursing homes, and they have a negative impact on quality of life. Developing and testing drugs for treating the LUT presents many challenges. Our goal is to develop a model that allows multiple urodynamic tests to be performed on a single animal over time. We compared the fidelity of bladder pressure recordings in male Sprague Dawley rats implanted with a standard bladder catheter that could be studied only a single time (control) to those obtained from animals implanted with various injection ports that facilitated multiple test sessions. Rats were placed into a cystometry cage allowing measurement of bladder pressure during continuous bladder filling with isotonic saline (175 μl/min). Micturition cycles were recorded until 3 consecutive cycles were reproducible. Rats with a fluid‐reservoir injection port showed higher pressures compared to control rats. Control rat bladder pressures were 8.1 ± 0.5, 12.4 ± 0.7, 14.6 ± 0.5, and 45.2 ± 2.1 mmHg for minimum, average, threshold, and maximum. In contrast, rats tested with the reservoir injection port showed pressures (mmHg) of: 11.4 ± 1.1, 17.0 ± 1.6, 21.8 ± 2.3, and 64.0 ± 4.5. Bladder pressure also exhibited large oscillations in rats with reservoir ports. In another group of rats, an infusion port lacking the fluid reservoir resulted in pressures that were comparable to control rats. In conclusion, conducting urodynamic tests in animals implanted with injection ports will allow stages of a disease, such as over active bladder, to be characterized in individual subjects.