Efficacy of a novel device for assessment of autonomic sensory function in the rat bladder

Purpose: We developed and tested the efficacy of an implantable bladder device which, when combined with the Neurometer (R), can be used to assess fiber specific afferent bladder sensation in the rat. Materials and Methods: We developed an implantable bladder device that applies selective nerve fiber stimuli (250 Hz for small myelinated A delta fibers and 5 Hz for unmyelinated C fibers) to the bladder mucosa in the rat to determine bladder sensory perception threshold values. We performed 3 experiments in 55 female Sprague-Dawley rats to examine the effects of our device on voiding habits, assess the interobserver reliability of the sensory perception threshold and determine the effects of intravesical administration of resiniferatoxin (Sigma (R)) and lidocaine on the sensory perception threshold. Results: Sensory perception threshold values obtained by 2 blinded, independent observers were not different from each other (p = 0.41). Sensory perception threshold values obtained at the 2 stimulation frequencies remained constant for at least 3 weeks after device implantation. A significant increase in sensory perception threshold values after resiniferatoxin instillation was noted at a stimulus frequency of 5 Hz (p = 0.02), whereas intravesical lidocaine led to an immediate increase in the sensory perception threshold at 250 and 5 Hz. Device implantation led to an early decreased voided volume and increased frequency of voids, although these parameters returned to normal after 4 days. Conclusions: Assessment of bladder afferent sensation with our newly developed device is feasible in rats. It provides sensory perception thresholds that appear to be fiber-type selective for autonomic bladder afferent nerves.