title: Inverse relationship of Rho kinase and myosin-light chain kinase expression in the aging human detrusor smooth muscle.
abstract: BACKGROUND
  Rho kinase (ROCK) and myosin-light chain kinase (MLCK) are key enzymes in smooth muscle contraction. Previous data have suggested that ROCK contribution to human detrusor contraction is increasing with age. Here, we have analyzed the transcriptional expression of Rho kinase isoforms (ROCK1 and ROCK2) as well as MLCK in the aging human detrusor smooth muscle obtained from resected tissue.
  
  
  METHODS
  Small pieces of macroscopically healthy human detrusor smooth muscle (urothelium-free) were prepared for quantitative real-time reverse transcriptase polymerase chain reaction (RT-PCR). Transcript expression (mRNA level) of the target genes ROCK1, ROCK2 and MLCK was normalized to three common reference genes (glyceraldehyde-3-phosphate dehydrogenase, β-actin, phosphoglycerate kinase 1).
  
  
  RESULTS
  We found that across all ages the expression level of ROCK (i.e. ROCK1 and ROCK2 together) was almost equal to that of MLCK in the human bladder. Further, ROCK2 showed a significantly higher expression level than ROCK1. Among all subjects, there was no significant correlation of any single target gene to age, but expression levels of ROCK and MLCK were inversely correlated. Moreover, the within-subject analysis revealed that the ROCK-to-MLCK ratio showed a significantly negative correlation to age. Thus, within a given subject, there is a relative ROCK down-regulation and concomitant MLCK up-regulation.
  
  
  CONCLUSIONS
  Together with previous data in human detrusor specimens showing increased ROCK contribution to detrusor contraction, we speculate that the drop of the ROCK-to-MLCK ratio may occur as an attempt to compensate for the increased Rho kinase activity.
authors.affiliation: Oscar Langendorff Institute of Physiology, University of Rostock, Gertrudenstrasse 9, 18057, Rostock, Germany. timo.kirschstein@uni-rostock.de.
authors.forename: Timo
authors.initials: T
authors.lastname: Kirschstein
authors.affiliation: Oscar Langendorff Institute of Physiology, University of Rostock, Gertrudenstrasse 9, 18057, Rostock, Germany. theresasahre@gmx.de.
authors.forename: Theresa
authors.initials: T
authors.lastname: Sahre
authors.affiliation: Department of Urology, University of Rostock, Rostock, Germany. karoline.kernig@med.uni-rostock.de.
authors.forename: Karoline
authors.initials: K
authors.lastname: Kernig
authors.affiliation: Department of Urology, University of Rostock, Rostock, Germany. chris.protzel@med.uni-rostock.de.
authors.forename: Chris
authors.initials: C
authors.lastname: Protzel
authors.affiliation: Oscar Langendorff Institute of Physiology, University of Rostock, Gertrudenstrasse 9, 18057, Rostock, Germany. Katrin.porath@uni-rostock.de.
authors.forename: Katrin
authors.initials: K
authors.lastname: Porath
authors.affiliation: Oscar Langendorff Institute of Physiology, University of Rostock, Gertrudenstrasse 9, 18057, Rostock, Germany. ruediger.koehling@uni-rostock.de.
authors.forename: Rüdiger
authors.initials: R
authors.lastname: Köhling
authors.affiliation: Department of Urology, University of Rostock, Rostock, Germany. oliver.hakenberg@med.uni-rostock.de.
authors.forename: Oliver W
authors.initials: OW
authors.lastname: Hakenberg
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000378:metabolism*; D005260:Female; D018507:Gene Expression Regulation, Developmental / Q000502:physiology; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D008875:Middle Aged; D009130:Muscle, Smooth / Q000201:enzymology*; D001743:Urinary Bladder / Q000201:enzymology*; D054460:rho-Associated Kinases / Q000378:metabolism*
chemical_list: C515851:ROCK1 protein, human; C515852:ROCK2 protein, human; D054460:rho-Associated Kinases