title: Somatic modulation of spinal reflex bladder activity mediated by nociceptive bladder afferent nerve fibers in cats.
abstract: The goal of the present study was to determine if supraspinal pathways are necessary for inhibition of bladder reflex activity induced by activation of somatic afferents in the pudendal or tibial nerve. Cats anesthetized with α-chloralose were studied after acute spinal cord transection at the thoracic T9/T10 level. Dilute (0.25%) acetic acid was used to irritate the bladder, activate nociceptive afferent C-fibers, and trigger spinal reflex bladder contractions (amplitude: 19.3 ± 2.9 cmH2O). Hexamethonium (a ganglionic blocker, intravenously) significantly (P < 0.01) reduced the amplitude of the reflex bladder contractions to 8.5 ± 1.9 cmH2O. Injection of lidocaine (2%, 1-2 ml) into the sacral spinal cord or transection of the sacral spinal roots and spinal cord further reduced the contraction amplitude to 4.2 ± 1.3 cmH2O. Pudendal nerve stimulation (PNS) at frequencies of 0.5-5 Hz and 40 Hz but not at 10-20 Hz inhibited reflex bladder contractions, whereas tibial nerve stimulation (TNS) failed to inhibit bladder contractions at all tested frequencies (0.5-40 Hz). These results indicate that PNS inhibition of nociceptive afferent C-fiber-mediated spinal reflex bladder contractions can occur at the spinal level in the absence of supraspinal pathways, but TNS inhibition requires supraspinal pathways. In addition, this study shows, for the first time, that after acute spinal cord transection reflex bladder contractions can be triggered by activating nociceptive bladder afferent C-fibers using acetic acid irritation. Understanding the sites of action for PNS or TNS inhibition is important for the clinical application of pudendal or tibial neuromodulation to treat bladder dysfunctions.
authors: Department of Urology, The Second Hospital, Shandong University, Jinan, China; Department of Urology, University of Pittsburgh, Pittsburgh, Pennsylvania; and.
authors: Zhiying
authors: Z
authors: Xiao
authors: Department of Urology, University of Pittsburgh, Pittsburgh, Pennsylvania; and.
authors: Marc J
authors: MJ
authors: Rogers
authors: Department of Urology, University of Pittsburgh, Pittsburgh, Pennsylvania; and.
authors: Bing
authors: B
authors: Shen
authors: Department of Urology, University of Pittsburgh, Pittsburgh, Pennsylvania; and.
authors: Jicheng
authors: J
authors: Wang
authors: Department of Urology, University of Pittsburgh, Pittsburgh, Pennsylvania; and.
authors: Zeyad
authors: Z
authors: Schwen
authors: Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, Pennsylvania.
authors: James R
authors: JR
authors: Roppolo
authors: Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, Pennsylvania.
authors: William C
authors: WC
authors: de Groat
authors: Department of Urology, University of Pittsburgh, Pittsburgh, Pennsylvania; and Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, Pennsylvania cftai@pitt.edu.
authors: Changfeng
authors: C
authors: Tai
mesh_terms: D019342:Acetic Acid; D000344:Afferent Pathways / Q000503:physiopathology; D000818:Animals; D002415:Cats; D005260:Female; D008297:Male; D059225:Nociception; D060525:Pudendal Nerve / Q000503:physiopathology*; D011897:Random Allocation; D012018:Reflex; D013119:Spinal Cord Injuries / Q000503:physiopathology*; D013904:Thoracic Vertebrae; D013979:Tibial Nerve / Q000503:physiopathology*; D001743:Urinary Bladder / Q000503:physiopathology*
chemical_list: D019342:Acetic Acid
keywords: cat; neuromodulation; pudendal; tibial; urinary bladder