title: Intraurethral stimulation evokes bladder responses via 2 distinct reflex pathways.
abstract: OBJECTIVE
  Recent animal studies have shown that selective activation of pudendal nerve branches can evoke bladder responses through 2 distinct reflex pathways. We examined intraurethral electrical stimulation as a minimally invasive means of selectively activating these pathways in the cat.
  
  
  METHODS
  Bladder responses evoked by intraurethral electrical stimulation were measured in alpha-chloralose anesthetized male cats at different stimulation frequencies, stimulation intensities and intraurethral locations.
  
  
  RESULTS
  Intraurethral electrical stimulation evoked inhibitory and excitatory bladder reflexes depending on stimulation frequency and location. Stimulation in the penile urethra 0 to 3 cm from the urethral meatus at 33 Hz evoked bladder contraction and at 10 Hz it evoked bladder relaxation. These responses were abolished after bilateral transection of the dorsal penile nerves. Stimulation in the membranous urethra 5 to 7 cm from the urethral meatus at 2, 10 and 33 Hz evoked bladder contractions. These responses were abolished after bilateral transection of the cranial sensory nerves. Following acute spinal cord transection bladder contractions were still evoked by 33 Hz stimulation in the penile urethra but not by stimulation at any frequency in the membranous urethra.
  
  
  CONCLUSIONS
  Intraurethral electrical stimulation selectively evoked bladder responses by activating 2 distinct pudendal afferent pathways. Responses depended on stimulation frequency and location. Intraurethral electrical stimulation is a valid means of determining the pathways involved in bladder responses evoked by pudendal nerve stimulation.
authors.affiliation: Department of Biomedical Engineering, Duke University, Durham, North Carolina 27708-0281, USA.
authors.forename: John P
authors.initials: JP
authors.lastname: Woock
authors.forename: Paul B
authors.initials: PB
authors.lastname: Yoo
authors.forename: Warren M
authors.initials: WM
authors.lastname: Grill
mesh_terms: D000344:Afferent Pathways; D000818:Animals; D002415:Cats; D004195:Disease Models, Animal; D004558:Electric Stimulation / Q000379:methods*; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D009130:Muscle, Smooth / Q000294:innervation* / Q000502:physiology; D011897:Random Allocation; D012018:Reflex / Q000502:physiology; D012680:Sensitivity and Specificity; D013119:Spinal Cord Injuries; D014521:Urethra / Q000294:innervation / Q000502:physiology; D001743:Urinary Bladder / Q000294:innervation* / Q000502:physiology; D017833:Visceral Afferents / Q000502:physiology*