title: Association of muscarinic M₃ receptors and Kir6.1 with caveolae in human detrusor muscle.
abstract: Caveolae are 50-100 nm large membrane invaginations that play a role in cellular signaling. The aim of the present study was to assess whether muscarinic M₃ receptors and the K(ATP) channel subunit Kir6.1 are associated with human detrusor caveolae, and to pharmacologically assess the relevance of this organization for contractility. Detrusor strips were dissected and used in ultrastructural, biochemical and mechanical studies. Caveolae were manipulated by cholesterol desorption using mβcd (methyl-β-cyclodextrin). Mβcd disrupted caveolae and caused a cholesterol-dependent ~3-fold rightward shift of the concentration-response curve for the muscarinic receptor agonist carbachol. The effect of mβcd was inhibited by the K(ATP) blockers glibenclamide, repaglinide and PNU-37883, and it was mimicked by the K(ATP) activator levcromakalim. Immunoelectron microscopy showed muscarinic M₃ receptors and Kir6.1 to be enriched in caveolae. In conclusion, pharmacological K(ATP) channel inhibition antagonizes the effect of caveolae disruption on muscarinic contractility in the human detrusor, and the K(ATP) channel subunit Kir6.1 co-localizes with M₃ receptors in caveolae.
authors.affiliation: Department of Experimental Medical Science, Lund University, Biomedical Centre, BMC D12, SE-221 84 Lund, Sweden.
authors.forename: Mari
authors.initials: M
authors.lastname: Ekman
authors.forename: Catarina
authors.initials: C
authors.lastname: Rippe
authors.forename: Mardjaneh Karbalaei
authors.initials: MK
authors.lastname: Sadegh
authors.forename: Saeed
authors.initials: S
authors.lastname: Dabestani
authors.forename: Matthias
authors.initials: M
authors.lastname: Mörgelin
authors.forename: Bengt
authors.initials: B
authors.lastname: Uvelius
authors.forename: Karl
authors.initials: K
authors.lastname: Swärd
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism; D000368:Aged; D021941:Caveolae / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D005260:Female; D015870:Gene Expression; D006801:Humans; D066298:In Vitro Techniques; D054086:KATP Channels / Q000819:agonists / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D008297:Male; D049990:Membrane Transport Modulators / Q000494:pharmacology; D018721:Muscarinic Agonists / Q000494:pharmacology; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D024661:Potassium Channels, Inwardly Rectifying / Q000235:genetics / Q000378:metabolism; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D021122:Protein Subunits / Q000819:agonists / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D021381:Protein Transport / Q000187:drug effects; D012333:RNA, Messenger / Q000378:metabolism; D043587:Receptor, Muscarinic M3 / Q000819:agonists / Q000378:metabolism*; D011955:Receptors, Drug / Q000235:genetics / Q000378:metabolism; D064233:Sulfonylurea Receptors; D001743:Urinary Bladder / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D047392:beta-Cyclodextrins / Q000037:antagonists & inhibitors / Q000494:pharmacology; D000099161:Kcnj11 Channel
chemical_list: D018528:ATP-Binding Cassette Transporters; D054086:KATP Channels; D049990:Membrane Transport Modulators; D018721:Muscarinic Agonists; D024661:Potassium Channels, Inwardly Rectifying; D020033:Protein Isoforms; D021122:Protein Subunits; D012333:RNA, Messenger; D043587:Receptor, Muscarinic M3; D011955:Receptors, Drug; D064233:Sulfonylurea Receptors; D047392:beta-Cyclodextrins; D000099161:Kcnj11 Channel; C108732:methyl-beta-cyclodextrin; C092520:uK-ATP-1 potassium channel