title: EP3 activation facilitates bladder excitability via HCN channels on ICCs.
abstract: EP3 is a receptor for prostaglandin E2 (PGE2), and although its effect on bladder excitability has attracted considerable attention, the underlying mechanism remains unclear. To investigate whether the hyperpolarization-activated cyclic nucleotide-gated (HCN) channels in the interstitial cells of Cajal (ICCs) of the bladder are involved in the effect of EP3 activation on bladder excitability, wild-type mice, HCN1 knockout (HCN1-/-) mice and rats were used in our study. Double immunofluorescence staining and immunoprecipitation assays demonstrated the interaction between EP3 and the HCN channels. Sulprostone is a selective agonist of EP3. The current density of HCN channels was enhanced by sulprostone or PGE2 using whole-cell patch clamping. Western blot analyses showed that the expression levels of HCN1 and HCN4 were higher in bladders that had undergone intravesical instillation with sulprostone than in bladders treated with normal saline (NS). Both PGE2 and sulprostone increased the calcium concentration of the ICCs, and their effects were inhibited by ZD7288 (antagonist of HCN channels) treatment. In bladder detrusor strip testing, both PGE2 and sulprostone enhanced the amplitude of the bladder detrusor in HCN1-/-mice; however, these effects were less than those in the wild-type mice. Furthermore, the effects of PGE2 and sulprostone were inhibited by ZD7288. Taken together, our results indicate that EP3 is expressed in bladder ICCs and facilitates bladder excitability via HCN channels. This study provides more comprehensive insights into the mechanism between inflammation and bladder excitability and highlights methods that can resolve bladder hyperactivity.
authors.affiliation: Department of Urology, Second Affiliated Hospital, Third Military Medical University, Chongqing 400037, China.
authors.forename: Chao
authors.initials: C
authors.lastname: Wu
authors.affiliation: Department of Urology, Second Affiliated Hospital, Third Military Medical University, Chongqing 400037, China.
authors.forename: Xingyou
authors.initials: X
authors.lastname: Dong
authors.affiliation: Department of Urology, Second Affiliated Hospital, Third Military Medical University, Chongqing 400037, China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Liu
authors.affiliation: Department of Urology, Second Affiliated Hospital, Third Military Medical University, Chongqing 400037, China.
authors.forename: Jingzhen
authors.initials: J
authors.lastname: Zhu
authors.affiliation: Department of Urology, Second Affiliated Hospital, Third Military Medical University, Chongqing 400037, China.
authors.forename: Teng
authors.initials: T
authors.lastname: Zhang
authors.affiliation: Department of Urology, Second Affiliated Hospital, Third Military Medical University, Chongqing 400037, China.
authors.forename: Qingqing
authors.initials: Q
authors.lastname: Wang
authors.affiliation: Department of Urology, Second Affiliated Hospital, Third Military Medical University, Chongqing 400037, China.
authors.forename: Xiaoyang
authors.initials: X
authors.lastname: Hu
authors.affiliation: Department of Urology, Second Affiliated Hospital, Third Military Medical University, Chongqing 400037, China.
authors.forename: Zhenxing
authors.initials: Z
authors.lastname: Yang
authors.affiliation: Department of Urology, Second Affiliated Hospital, Third Military Medical University, Chongqing 400037, China. Electronic address: lilongk@hotmail.com.
authors.forename: Longkun
authors.initials: L
authors.lastname: Li
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D015232:Dinoprostone / Q000031:analogs & derivatives / Q000494:pharmacology; D005260:Female; D064428:Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D056885:Interstitial Cells of Cajal / Q000187:drug effects / Q000378:metabolism*; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D018613:Microscopy, Confocal; D009119:Muscle Contraction / Q000187:drug effects; D011485:Protein Binding; D011743:Pyrimidines / Q000494:pharmacology; D017207:Rats, Sprague-Dawley; D058308:Receptors, Prostaglandin E, EP3 Subtype / Q000819:agonists / Q000378:metabolism*; D001743:Urinary Bladder / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*
chemical_list: D064428:Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels; D011743:Pyrimidines; D058308:Receptors, Prostaglandin E, EP3 Subtype; C082246:ICI D2788; C016767:sulprostone; D015232:Dinoprostone; D002118:Calcium
keywords: Bladder excitability; EP3; HCN channels; ICCs