title: Obstruction enhances rho-kinase pathway and diminishes protein kinase C pathway in carbachol-induced calcium sensitization in contraction of α-toxin permeabilized guinea pig detrusor smooth muscle.
abstract: OBJECTIVE
  We investigated the relative important role of rho kinase (ROK) and protein kinase C (PKC) pathways in carbachol (CCh)-induced Ca(2+) sensitization in α-toxin permeabilized Guinea pig detrusor smooth muscle (DSM) following bladder outlet obstruction (BOO).
  
  
  METHODS
  Bladder outlet obstruction was created by placement of a silver jeweler's jump rings loosely round the urethro-vesical junction of Guinea pigs. Sham operated Guinea pig underwent a similar protocol without application of the ring and served as control. α-Toxin permeabilized DSM strips from control Guinea pigs and those subjected to 6-8 weeks of BOO were mounted horizontally for isometric force recording in 100 µl relaxing solution on perspex block. The effect of ROK inhibitor (Y-27632) and PKC inhibitor (GF-109203X) on CCh-induced Ca(2+) sensitization was studied during sustained contraction. Permeabilized DSM strips were also stimulated by cumulative increase of Ca(2+) concentration compared to that in control in the presence and in the absence of sensitization-induced PKC activator, phorbol 12,13-dibutyrate.
  
  
  RESULTS
  Ca(2+) sensitization-induced by CCh was greater in BOO compared to controls. This muscarinic agonist-induced Ca(2+) sensitization was inhibited by Y-27632 or GF-109203X. The inhibitory effect of Y-27632 (5 µM) was greater while the inhibitory effect of GF-109203X (5 µM) was smaller in BOO compared to that in controls. Phorbol 12,13-dibutyrate (1 µM) markedly increased Ca(2+) sensitivity in controls but not in BOO.
  
  
  CONCLUSIONS
  Our findings provide the first evidence that BOO enhances the ROK pathway and diminishes the PKC pathway in CCh-induced Ca(2+) sensitization in contraction of permeabilized Guinea pig DSM and suggest that inhibitors of ROK might potentially relieve bladder dysfunction related to BOO.
authors.affiliation: Department of Urology, Kyushu University, Fukuoka, Japan.
authors.forename: Nouval
authors.initials: N
authors.lastname: Shahab
authors.forename: Shunichi
authors.initials: S
authors.lastname: Kajioka
authors.forename: Fumi
authors.initials: F
authors.lastname: Takahashi-Yanaga
authors.forename: Mitsuho
authors.initials: M
authors.lastname: Onimaru
authors.forename: Miho
authors.initials: M
authors.lastname: Matsuda
authors.forename: Narihito
authors.initials: N
authors.lastname: Seki
authors.forename: Seiji
authors.initials: S
authors.lastname: Naito
mesh_terms: D000577:Amides / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002217:Carbachol / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006168:Guinea Pigs; D007211:Indoles / Q000494:pharmacology; D008297:Male; D008301:Maleimides / Q000494:pharmacology; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology*; D009130:Muscle, Smooth / Q000187:drug effects / Q000502:physiology*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011725:Pyridines / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D001748:Urinary Bladder Neck Obstruction / Q000378:metabolism*; D054460:rho-Associated Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*
chemical_list: D000577:Amides; D004791:Enzyme Inhibitors; D007211:Indoles; D008301:Maleimides; D011725:Pyridines; C108830:Y 27632; D002217:Carbachol; D054460:rho-Associated Kinases; D011493:Protein Kinase C; C070515:bisindolylmaleimide I; D002118:Calcium