title: Protein kinase C modulates frequency of micturition and non-voiding contractions in the urinary bladder via neuronal and myogenic mechanisms.
abstract: BACKGROUND
  Protein Kinase C (PKC) dysfunction is implicated in a variety of smooth muscle disorders including detrusor overactivity associated with frequency and urgency of micturition. In this study, we aimed to evaluate the modulatory effects of endogenous PKC-dependent pathways on bladder storage and emptying function.
  
  
  METHODS
  We utilized in vivo cystometry and in vitro organ bath studies using isolated bladder muscle strips (BMS) from rats to measure contractility, intravesical pressure, and voided volume. Both in vitro and in vivo results were statistically analyzed using one-way repeated measures ANOVA between the groups followed by Bonferroni's post-test, as appropriate (Systat Software Inc., San Jose, CA).
  
  
  RESULTS
  Effects of PKC activators, phorbol-12,13-dibutyrate (PDBu), and phorbol-12,13-myristate (PMA), were concentration-dependent, with high concentrations increasing frequency of micturition, and sensitivity of intramural nerves to electrical field stimulation (EFS), in vitro, while lower concentrations had no effect on BMS sensitivity to EFS. The PKC inhibitors, bisindolylmaleimide1 (Bim-1), (28 nM), and Ro318220 (50 μM) triggered an increase in the number of non-voiding contractions (NVC), and a decrease in the voided volume associated with reduced ability to maintain contractile force upon EFS, but did not affect peak force in vitro. Both low (50 nM) and high PDBu 1 micromolar (1 uM) decreased the sensitivity of BMS to carbachol. Application of a low concentration of PDBu inhibited spontaneous contractions, in vitro, and Bim-1-induced NVC, and restored normal voiding frequency during urodynamic recordings in vivo.
  
  
  CONCLUSIONS
  In summary, the effects of low PKC stimulation include inhibition of smooth muscle contractile responses, whereas high levels of PKC stimulation increased nerve-mediated contractions in vitro, and micturition contractions in vivo. These results indicate that endogenous PKC signaling displays a concentration-dependent contraction profile in the urinary bladder via both smooth muscle and nerve-mediated pathways.
authors.affiliation: Division of Urology, Department of Surgery, University of Colorado Denver, Anschutz Medical Campus,12700 E 19th Ave, Mail Stop C317, Aurora, CO, 80045, USA. Joseph.Hypolite@ucdenver.edu.
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Hypolite
authors.affiliation: Department of Surgery, Cooper University, Camden, NJ, USA. Shaohuachang@verizon.net.
authors.forename: Shaohua
authors.initials: S
authors.lastname: Chang
authors.affiliation: Division of Urology, Department of Surgery, University of Pennsylvania, Philadelphia, PA, USA. Alan.Wein@uphs.upenn.edu.
authors.forename: Alan J
authors.initials: AJ
authors.lastname: Wein
authors.affiliation: Division of Urology, Department of Surgery, University of Pennsylvania, Philadelphia, PA, USA. Chackosk@vet.upenn.edu.
authors.forename: Samuel
authors.initials: S
authors.lastname: Chacko
authors.affiliation: Division of Urology, Department of Surgery, University of Colorado Denver, Anschutz Medical Campus,12700 E 19th Ave, Mail Stop C317, Aurora, CO, 80045, USA. Anna.Malykhina@ucdenver.edu.
authors.forename: Anna P
authors.initials: AP
authors.lastname: Malykhina
mesh_terms: D000818:Animals; D004305:Dose-Response Relationship, Drug; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects* / Q000502:physiology*; D015240:Phorbol 12,13-Dibutyrate / Q000494:pharmacology; D010703:Phorbol Esters / Q000494:pharmacology; D011493:Protein Kinase C / Q000502:physiology*; D017207:Rats, Sprague-Dawley; D001743:Urinary Bladder / Q000187:drug effects* / Q000502:physiology*; D014554:Urination / Q000187:drug effects* / Q000502:physiology*
chemical_list: D010703:Phorbol Esters; C119222:phorbol-12-myristate; D015240:Phorbol 12,13-Dibutyrate; D011493:Protein Kinase C