title: Age-dependent contribution of Rho kinase in carbachol-induced contraction of human detrusor smooth muscle in vitro.
abstract: OBJECTIVE
  Activation of muscarinic receptors on the detrusor smooth muscle is followed by contraction, which involves both myosin light chain kinase (MLCK) and Rho kinase (ROCK). The aim of this study was to determine the relative contributions of MLCK and ROCK to carbachol-induced contraction of human detrusor smooth muscle in vitro.
  
  
  METHODS
  Detrusor smooth muscle strips were prepared from the macroscopically unaffected bladder wall of patients underwent cystectomy. The strips were fixed in an organ bath, and carbachol or KCl-induced isometric contractions were measured by force transducers.
  
  
  RESULTS
  Addition of carbachol (0.4-4 μmol/L) into the bath induced concentration-dependent contractions of detrusor specimens, which was completely abolished by atropine (1 μmol/L). Pre-incubation of detrusor specimens with either the MLCK inhibitor ML-9 or the ROCK inhibitors HA1100 and Y-27632 (each at 10 μmol/L) significantly blocked carbachol-induced contractions as compared to the time-control experiments. Moreover, MLCK and ROCK inhibition were equally effective in reducing carbachol-induced contractions. The residual carbachol-induced contractions in the presence of both MLCK and ROCK inhibitors were significantly smaller than the contractions obtained when only one enzyme (either MLCK or ROCK) was inhibited, suggesting an additive effect of the two kinases. Interestingly, ROCK-mediated carbachol-induced contractions were positively correlated to the age of patients (r=o.52, P<0.05).
  
  
  CONCLUSIONS
  Both MLCK and ROCK contribute to carbachol-induced contractions of human detrusor smooth muscle. ROCK inhibitors may be a new pharmacological approach to modulate human bladder hyperactivity.
authors.affiliation: Oscar Langendorff Institute of Physiology, University of Rostock, Germany.
authors.forename: Timo
authors.initials: T
authors.lastname: Kirschstein
authors.affiliation: Department of Urology, University of Rostock, Medical Center, Germany.
authors.forename: Chris
authors.initials: C
authors.lastname: Protzel
authors.affiliation: Oscar Langendorff Institute of Physiology, University of Rostock, Germany.
authors.forename: Katrin
authors.initials: K
authors.lastname: Porath
authors.affiliation: Oscar Langendorff Institute of Physiology, University of Rostock, Germany.
authors.forename: Tina
authors.initials: T
authors.lastname: Sellmann
authors.affiliation: Oscar Langendorff Institute of Physiology, University of Rostock, Germany.
authors.forename: Rüdiger
authors.initials: R
authors.lastname: Köhling
authors.affiliation: Department of Urology, University of Rostock, Medical Center, Germany.
authors.forename: Oliver W
authors.initials: OW
authors.lastname: Hakenberg
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000187:drug effects / Q000378:metabolism*; D002217:Carbachol / Q000494:pharmacology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology*; D009130:Muscle, Smooth / Q000187:drug effects / Q000201:enzymology*; D009924:Organ Culture Techniques; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D001743:Urinary Bladder / Q000187:drug effects / Q000201:enzymology*; D054460:rho-Associated Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*
chemical_list: D047428:Protein Kinase Inhibitors; D002217:Carbachol; D054460:rho-Associated Kinases