Purpose-We developed and tested the efficacy of an implantable bladder device which, when combined with the Neurometer®, can be used to assess fiber-specific afferent sensation of the bladder in the rat.Materials and Methods-We developed an implantable bladder device which applies selective nerve fiber stimuli (250 Hz for small myelinated (Aδ), and 5 Hz for unmyelinated (C) fibers) to the bladder mucosa in the rat in order to obtain the bladder sensory perception threshold (SPT) values. We performed three experiments on fifty-five female Sprague-Dawley rats, examining the effects of our device on voiding habits; assessing the inter-observer reliability of SPT; and the effects of intravesical administration of resiniferatoxin and lidocaine on the SPT.
Results-The SPT values obtained by two blinded, independent observers were not different from one another (p= 0.41). The SPT values obtained at both stimulation frequencies remained constant for at least 3 weeks after device implantation. A significant increase in SPT values after instillation of resiniferatoxin (p = 0.02) was noted at a stimulus frequency of 5 Hz, whereas intravesical lidocaine led to an immediate increase in SPT at both 250 and 5 Hz. Device implantation led to an early decreased voided volume and increased frequency of voids, however these parameters returned to normal after 4 days.Conclusions-Assessment of bladder afferent sensation with our newly developed device is feasible in rats, and provides sensory perception thresholds that appear to be fiber-type selective for autonomic bladder afferent nerves.