title: Effect of S-methyl-l-thiocitrulline dihydrochloride on rat micturition reflex.
abstract: OBJECTIVE
  To evaluate the effect of neuronal nitric oxide synthase on the striated urethral sphincter and the urinary bladder.
  
  
  METHODS
  A coaxial catheter was implanted in the proximal urethra and another one in the bladder of female rats, which were anesthetized with subcutaneous injection of urethane. The urethral pressure with saline continuous infusion and bladder isovolumetric pressure were simultaneously recorded. Two groups of rats were formed. In group I, an intrathecal catheter was implanted on the day of the experiment at the L6-S1 level of the spinal cord; in group II, an intracerebroventricular cannula was placed 5-6 days before the experiment.
  
  
  RESULTS
  It was verified that the group treated with S-methyl-L-thio-citrulline, via intrathecal pathway, showed complete or partial inhibition of the urethral sphincter relaxation and total inhibition of the micturition reflexes. The urethral sphincter and the detrusor functions were recovered after L-Arginine administration. When S-methyl-Lthio-citrulline was administered via intracerebroventricular injection, there was a significant increase of urethral sphincter tonus while preserving the sphincter relaxation and the detrusor contractions, at similar levels as before the use of the drugs. Nevertheless there was normalization of the urethral tonus when L-Arginine was applied.
  
  
  CONCLUSIONS
  The results indicate that, in female rats anaesthetized with urethane, the nNOS inhibitor administrated through the intrathecal route inhibits urethral sphincter relaxation, while intracerebroventricular injection increases the sphincter tonus, without changing bladder function. These changes were reverted by L-Arginine administration. These findings suggest that the urethral sphincter and detrusor muscle function is modulated by nitric oxide.
authors.affiliation: Divisão de Urologia, Faculdade de Medicina Ribeirão Preto, Universidade de São Paulo, SP, Brasil.
authors.forename: Jeová Nina
authors.initials: JN
authors.lastname: Rocha
mesh_terms: D018686:Anesthetics, Intravenous; D000818:Animals; D001120:Arginine / Q000494:pharmacology; D002956:Citrulline / Q000031:analogs & derivatives* / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005260:Female; D007278:Injections, Spinal; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology; D052248:Nitric Oxide Synthase Type I / Q000494:pharmacology*; D011312:Pressure; D017208:Rats, Wistar; D012016:Reference Values; D013890:Thiourea / Q000031:analogs & derivatives* / Q000494:pharmacology; D013997:Time Factors; D014520:Urethane / Q000494:pharmacology; D014521:Urethra / Q000187:drug effects* / Q000502:physiology; D001743:Urinary Bladder / Q000187:drug effects* / Q000502:physiology; D014554:Urination / Q000187:drug effects* / Q000502:physiology
chemical_list: D018686:Anesthetics, Intravenous; D004791:Enzyme Inhibitors; D002956:Citrulline; D014520:Urethane; D001120:Arginine; D052248:Nitric Oxide Synthase Type I; D013890:Thiourea; C086717:S-methylthiocitrulline
keywords: Nitric Oxide Synthase; Urethra; Urinary Sphincter, Artificial