title: Increased transient receptor potential vanilloid type 1 (TRPV1) signaling in idiopathic overactive bladder urothelial cells.
abstract: OBJECTIVE
  To measure transient receptor potential vanilloid type 1 (TRPV1) signaling in human bladder urothelial cells (BUC) from non-neurogenic overactive bladder (OAB) patients and control subjects (NB) BUC.
  
  
  METHODS
  Primary BUC cell cultures were derived from cystoscopic biopsies from two OAB and two NB subjects. TRPV1 expression was detected by immunofluorescence, PCR and Western blot staining. TRPV1 function was assessed by capsaicin (CAP, 6 µM)-evoked intracellular calcium ([Ca(2+)](i)) changes measured by microfluorimetry imaging. CAP evoked changes in inward and outward currents were recorded electrophysiologically using excised outside-out patches and whole cell configurations using various protocols.
  
  
  RESULTS
  OAB BUC had significantly increased expression of TRPV1 compared to NB BUC on Western blot. CAP evoked significantly higher maximal [Ca(2+)](i) change over baseline in OAB (84.71 ± 8.96%) compared to NB BUC (60.32 ± 7.93%) (P < 0.05). CAP induced significantly greater percent change in single channel open probability (205.94 ± 20.53% OAB vs. 141.26 ± 16.53% NB, P < 0.05) and normalized inward currents (13.54 ± 1.6 4 pA/pF OAB vs. 8.28 ± 0.89 pA/pF NB, P < 0.05). CAP caused significantly higher percent increase from baseline of whole cell outward currents in OAB (177.12 ± 44.46%) compared to NB BUC (135.98 ± 44.28%) (P < 0.05). Similarly thermal stimulus (45°C solution) evoked significantly higher percent increase in whole cell outward currents in OAB (183.93 ± 14.07%) compared to NB (145.61 ± 10.12%) BUC (P < 0.05). These responses were blocked by 10 µM capsazepine (CPZ), a TRPV1 antagonist.
  
  
  CONCLUSIONS
  Because only a few subjects were studied, augmented TRPV1 signaling cannot be generalized to all OAB subjects. However, the findings are consistent with the hypothesis that BUC are involved in sensory signaling.
authors.affiliation: Division of Urology, Department of Surgery, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA.
authors.forename: Mingkai
authors.initials: M
authors.lastname: Li
authors.forename: Yan
authors.initials: Y
authors.lastname: Sun
authors.forename: J Marc
authors.initials: JM
authors.lastname: Simard
authors.forename: Toby C
authors.initials: TC
authors.lastname: Chai
mesh_terms: D000328:Adult; D015153:Blotting, Western; D002478:Cells, Cultured; D004594:Electrophysiology; D004847:Epithelial Cells / Q000378:metabolism / Q000473:pathology; D005260:Female; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D006801:Humans; D018408:Patch-Clamp Techniques; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000502:physiology*; D050916:TRPV Cation Channels / Q000378:metabolism*; D001743:Urinary Bladder / Q000378:metabolism* / Q000473:pathology; D053201:Urinary Bladder, Overactive / Q000378:metabolism* / Q000473:pathology; D019459:Urothelium / Q000378:metabolism* / Q000473:pathology
chemical_list: D050916:TRPV Cation Channels; C494482:TRPV1 protein, human