title: The role of TRPM8 in the Guinea-pig bladder-cooling reflex investigated using a novel TRPM8 antagonist.
abstract: Patients with overactive bladder often exhibit abnormal bladder contractions in response to intravesical cold saline (positive ice-water test). The molecular entity involved in cold sensation within the urinary bladder is unknown, but a potential candidate is the ion channel, transient receptor potential (melastatin)-8 (TRPM8). The objective of the present study was to investigate the role of TRPM8 in a bladder-cooling reflex evoked in anaesthetised guinea-pigs that is comparable to the positive ice-water test seen in patients. Guinea-pig TRPM8 was cloned from L6 dorsal root ganglia (DRG) and expressed in HEK293 cells. Functional agonist- and cold-induced Ca2+ influx and electrophysiology assays were performed in these cells, and for comparison in HEK293 cells expressing human TRPM8, using a novel TRPM8 antagonist, the S-enantiomer of 1-phenylethyl 4-(benzyloxy)-3-methoxybenzyl (2-aminoethyl) carbamate hydrochloride (PBMC). Potency data from these assays was used to calculate intravenous infusion protocols for targeted plasma concentrations of PBMC in studies on micturition reflexes evoked by intravesical infusion of menthol or cold saline in anaesthetised guinea-pigs. Tissue expression of TRPM8 in guinea-pig bladder, urethra and in dorsal root ganglia neurones traced from the bladder was also investigated. TRPM8 mRNA and protein were detected in L6 dorsal root ganglia, bladder urothelium and smooth muscle. PBMC antagonised in vitro activation of human and guinea-pig TRPM8 and reversed menthol and cold-induced facilitation of the micturition reflex at plasma concentrations consistent with in vitro potencies. The present data suggest that the bladder-cooling reflex in the guinea-pig involves TRPM8. The potential significance of TRPM8 in bladder disease states deserves future investigation.
authors: Discovery Biology, Pfizer Global R&D, Sandwich, Kent, CT13 9NJ, United Kingdom,. Electronic address: jengardiner@btinternet.com.
authors: Jennifer C
authors: JC
authors: Gardiner
authors: Discovery Biology, Pfizer Global R&D, Sandwich, Kent, CT13 9NJ, United Kingdom,. Electronic address: anthonykirkup@pfizer.com.
authors: Anthony J
authors: AJ
authors: Kirkup
authors: Discovery Biology, Pfizer Global R&D, Sandwich, Kent, CT13 9NJ, United Kingdom,. Electronic address: currjohn@gmail.com.
authors: John
authors: J
authors: Curry
authors: Discovery Biology, Pfizer Global R&D, Sandwich, Kent, CT13 9NJ, United Kingdom,. Electronic address: sian.humphreys@pfizer.com.
authors: Sian
authors: S
authors: Humphreys
authors: Discovery Biology, Pfizer Global R&D, Sandwich, Kent, CT13 9NJ, United Kingdom,. Electronic address: poregan75@googlemail.com.
authors: Paul
authors: P
authors: O'Regan
authors: Discovery Biology, Pfizer Global R&D, Sandwich, Kent, CT13 9NJ, United Kingdom,. Electronic address: michael.postlethwaite@bachem.com.
authors: Michael
authors: M
authors: Postlethwaite
authors: Discovery Biology, Pfizer Global R&D, Sandwich, Kent, CT13 9NJ, United Kingdom,. Electronic address: young_kimberley@yahoo.co.uk.
authors: Kimberley C
authors: KC
authors: Young
authors: Discovery Biology, Pfizer Global R&D, Sandwich, Kent, CT13 9NJ, United Kingdom,. Electronic address: lindakitching@yahoo.co.uk.
authors: Linda
authors: L
authors: Kitching
authors: Pharmacokinetics, Dynamics and Metabolism, Pfizer Global R&D, Sandwich, Kent, CT13 9NJ, United Kingdom. Electronic address: brian.ethell@novartis.com.
authors: Brian T
authors: BT
authors: Ethell
authors: Discovery Biology, Pfizer Global R&D, Sandwich, Kent, CT13 9NJ, United Kingdom.
authors: David
authors: D
authors: Winpenny
authors: Discovery Biology, Pfizer Global R&D, Sandwich, Kent, CT13 9NJ, United Kingdom,. Electronic address: gordon.mcmurray@pfizer.com.
authors: Gordon
authors: G
authors: McMurray
mesh_terms: D000813:Anilides / Q000494:pharmacology; D000818:Animals; D001833:Body Temperature Regulation; D002219:Carbamates / Q000494:pharmacology; D005260:Female; D005727:Ganglia, Spinal / Q000378:metabolism; D006168:Guinea Pigs; D057809:HEK293 Cells; D006801:Humans; D008297:Male; D008610:Menthol / Q000031:analogs & derivatives / Q000494:pharmacology; D009130:Muscle, Smooth / Q000378:metabolism; D009474:Neurons / Q000378:metabolism; D050053:TRPM Cation Channels / Q000819:agonists / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000502:physiology; D014521:Urethra / Q000378:metabolism; D001743:Urinary Bladder / Q000378:metabolism
chemical_list: D000813:Anilides; D002219:Carbamates; C533807:N-(4-methoxyphenyl)-4-menthone-3-carboxamide; D050053:TRPM Cation Channels; D008610:Menthol
keywords: (-) menthol (PubChem CID: 16666); 1-phenylethyl 4-(benzyloxy)-3-methoxybenzyl(2-aminoethyl) carbamate (PBMC) (PubChem CID: 73755215); Bladder; Cold; Guinea-pig; Menthol; Micturition; TRPM8; WS-12 (PubChem CID: 71311855)