1965 DOWN-REGULATION OF LARGE CONDUCTANCE, CALCIUM-ACTIVATED K+ CHANNEL GENE EXPRESSION IN MICE AND HUMAN DETRUSOR SMOOTH MUSCLE FOLLOWING PARTIAL BLADDER OUTLET OBSTRUCTION: EFFECTS OF STRETCH AND HYPOXIA

Abstract

You have accessJournal of UrologyUrodynamics/Incontinence/Female Urology: Non-Neurogenic Voiding Dysfunction1 Apr 20121965 DOWN-REGULATION OF LARGE CONDUCTANCE, CALCIUM-ACTIVATED K+ CHANNEL GENE EXPRESSION IN MICE AND HUMAN DETRUSOR SMOOTH MUSCLE FOLLOWING PARTIAL BLADDER OUTLET OBSTRUCTION: EFFECTS OF STRETCH AND HYPOXIA Ettickan Boopathi, Stephen Zderic, Sankar Addya, Paolo Fortina, Alan Wein, and Samuel Chacko Ettickan BoopathiEttickan Boopathi Glenolden, PA More articles by this author , Stephen ZdericStephen Zderic Philadelphia, PA More articles by this author , Sankar AddyaSankar Addya Philadelphia, PA More articles by this author , Paolo FortinaPaolo Fortina Philadelphia, PA More articles by this author , Alan WeinAlan Wein Philadelphia, PA More articles by this author , and Samuel ChackoSamuel Chacko Glenolden, PA More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2012.02.2124AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Large-conductance voltage- and calcium-activated potassium (BK) channels have been shown to play a role in detrusor overactivity (DO). Recently, our group demonstrated that the expression of BKα and the accessory β1 subunit was decreased in partial bladder outlet obstruction (PBOO)-induced DO in the rabbit model for PBOO and in men with BPH-induced PBOO. The loss of these proteins contributed to the spontaneous contractions and DO. Here we show that the expression of BKα and BKβ was downregulated in the detrusor smooth muscle (DSM) from 14-day obstructed murine bladders both at mRNA and protein levels. Since PBOO is associated with bladder wall stretch and hypoxia, we ask whether stretch or hypoxia contributes to the downregulation of BKα and BKβ expression. Data show that stretch and hypoxia down-regulate BKα and BKβ protein expression in a time dependent manner in cultured human primary bladder myocytes. METHODS Male C57Bl/6 mice were surgically obstructed and kept for 14 days. Sham-operated mice served as a control. Bladders were excised; urothelium scarped off with a scalpel, and the serosa was removed. DSM obtained from PBOO and sham control animals were used for microarray and western blotting. For stretch and hypoxia experiments, human primary bladder smooth muscle cells were seeded on type I collagen-coated silicone sheeting membrane at a density of 1 × 105 per well in M199 medium containing 10 percent FBS and grown to near confluence. Cells were rendered quiescent by incubation in medium containing 1 percent FBS for 48 hours and then subjected to cyclic stretch and 1 percent hypoxia independently for 24 and 48 hours. RESULTS Expression of BKα and BKβ in the DSM were decreased in 14-day obstructed groups both at the mRNA and protein levels as shown by microarray and immunoblotting compared to that of sham-operated animals. There was a significant time dependent downregulation of BKα and BKβ expression in stretch and hypoxia compared to un-stretched cells and cells grown in normal oxygen level. CONCLUSIONS These results confirm that the BKα and BKβ gene expression is downregulated in obstructed murine bladder smooth muscle. Based on our experimental data from cell culture experiments, mechanical stretch and hypoxia in the obstructed bladder are the initiating factors for the down regulation of BKα and BKβ gene expression in the DSM in PBOO observed in animal models and men. © 2012 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 187Issue 4SApril 2012Page: e793 Advertisement Copyright & Permissions© 2012 by American Urological Association Education and Research, Inc.MetricsAuthor Information Ettickan Boopathi Glenolden, PA More articles by this author Stephen Zderic Philadelphia, PA More articles by this author Sankar Addya Philadelphia, PA More articles by this author Paolo Fortina Philadelphia, PA More articles by this author Alan Wein Philadelphia, PA More articles by this author Samuel Chacko Glenolden, PA More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...