27 AFFERENT AND EFFERENT MECHANISMS ASSOCIATED WITH NEUROMODULATION OF THE BLADDER MICTURITION REFLEX IN THE RAT (2012)

You have accessJournal of UrologyUrodynamics/Incontinence/Female Urology: Basic Research I1 Apr 201227 AFFERENT AND EFFERENT MECHANISMS ASSOCIATED WITH NEUROMODULATION OF THE BLADDER MICTURITION REFLEX IN THE RAT Xin Su, Angela M. Nickles, and Dwight E. Nelson Xin SuXin Su Minneapolis, MN More articles by this author , Angela M. NicklesAngela M. Nickles Minneapolis, MN More articles by this author , and Dwight E. NelsonDwight E. Nelson Minneapolis, MN More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2012.02.070AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Spinal nerve stimulation (SNS, 10Hz) suppresses bladder micturition reflex contraction (BRC), either eliminating BRC or reducing the contraction frequency in a current dependent manner. Here we evaluate whether this suppression may be associated with increased bladder capacity (e.g. through afferent functions) or suppression of detrusor contractions (efferent functions). METHODS In female rats (urethane, i.p. 1.2g/kg), a monopolar electrode was placed under L6 spinal nerves. A bladder cannula was placed via the urethra for saline infusion and intravesical pressure recording. Saline infusion induced BRC. If SNS completely abolished BRC, we determined whether additional infusion could overcome bladder inhibition. RESULTS SNS attenuated the frequency but not amplitude of BRC. Two x motor threshold (2*Tmot), 3*Tmot, 4*Tmot and 6*Tmot significantly (p<0.05, vs. control, n=23) decreased the frequency of BRC during stimulation to 65.56 ± 17% (n=9), 10.64 ± 8% (n=8), 6.25 ± 6% (n=7), and 0% of controls (n=7), respectively. High intensity SNS abolished BRC. Additional saline re-established the BRC with a similar frequency but lower amplitude despite the presence of electrical stimulation (Fig 1A). During this time SNS produced a significant inhibition of the amplitude but not frequency of BRC (n=5, p<0.05, Fig 1B/C). CONCLUSIONS Bladder inhibitory effects of SNS are a consequence of an increased bladder capacity since SNS attenuates the frequency but not amplitude of BRC and the ‘shutdown' of the BRC can be re-established by additional saline infusion. Consistent with this, we previously reported that SNS increases voiding threshold and inter-contraction interval but not voiding pressure (Su et al., IPPS, 2011). However since SNS suppresses the amplitude of the re-established BRC, SNS may also directly depress detrusor contractility. These data suggest that SNS neuromodulation may act through two distinct stimulation modes. Lower stimulation intensities appear to be mediated through the afferent limb of the neural circuit and increase the bladder capacity. Higher intensities may additionally act through efferent neural pathways and attenuate amplitude of detrusor contractions as well as by increasing bladder capacity. © 2012 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 187Issue 4SApril 2012Page: e10-e11 Advertisement Copyright & Permissions© 2012 by American Urological Association Education and Research, Inc.Metrics Author Information Xin Su Minneapolis, MN More articles by this author Angela M. Nickles Minneapolis, MN More articles by this author Dwight E. Nelson Minneapolis, MN More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...