title: Strain-dependent urethral response.
abstract: OBJECTIVE
  The Sprague-Dawley (SD) rat, an out-bred, all-purpose strain, has served well for lower urinary tract research. However, to test new cellular therapies for conditions such as stress urinary incontinence, an in-bred rat strain with immune tolerance, such as the Lewis rat, may be more useful. The objective of this study was to reveal any differences in lower urinary tract continence mechanisms between the Lewis and SD rat.
  
  
  METHODS
  The contribution of (1) the striated and smooth muscle to the mechanical and functional properties of the urethra in vitro, and (2) the striated sphincter to leak point pressure (LPP) and reflex continence mechanisms in vivo were assessed in normal (control) Lewis and SD rats and in a model of stress urinary incontinence produced by bilateral pudendal nerve transection.
  
  
  RESULTS
  Control, Lewis rats had significantly lower LPP, significantly less fast-twitch skeletal muscle and relied less on the striated sphincter for continence than control, SD rats, as indicated by the failure of neuromuscular blockade with alpha-bungarotoxin to reduce LPP. Nerve transection significantly decreased LPP in the SD rat, but not in the Lewis rat. Although the Lewis urethra contained more smooth muscle than the SD rat, it was less active in vitro as indicated by a low urethral baseline pressure and lack of response to phenylephrine.
  
  
  CONCLUSIONS
  We have observed distinct differences in functional and mechanical properties of the SD and Lewis urethra and have shown that the Lewis rat may not be suitable as a chronic model of SUI via nerve transection.
authors.affiliation: Department of Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.
authors.forename: Donna J
authors.initials: DJ
authors.lastname: Haworth
authors.forename: Takeya
authors.initials: T
authors.lastname: Kitta
authors.forename: Brian
authors.initials: B
authors.lastname: Morelli
authors.forename: Douglas W
authors.initials: DW
authors.lastname: Chew
authors.forename: Naoki
authors.initials: N
authors.lastname: Yoshimura
authors.forename: William C
authors.initials: WC
authors.lastname: de Groat
authors.forename: David A
authors.initials: DA
authors.lastname: Vorp
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001696:Biomechanical Phenomena; D002038:Bungarotoxins / Q000494:pharmacology; D004195:Disease Models, Animal; D005260:Female; D010656:Phenylephrine / Q000494:pharmacology; D011312:Pressure; D060525:Pudendal Nerve / Q000601:surgery; D051381:Rats; D011917:Rats, Inbred Lew; D017207:Rats, Sprague-Dawley; D012018:Reflex; D012912:Sneezing; D013045:Species Specificity; D014521:Urethra / Q000187:drug effects / Q000294:innervation / Q000473:pathology / Q000503:physiopathology*; D014549:Urinary Incontinence / Q000209:etiology / Q000473:pathology / Q000503:physiopathology*; D014563:Urodynamics / Q000187:drug effects
chemical_list: D002038:Bungarotoxins; D010656:Phenylephrine; D000109:Acetylcholine