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This Article Full Text Full Text (PDF) All Versions of this Article: 294/4/F971    most recent 00313.2007v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Kullmann, F. A. Articles by Birder, L. A. Search for Related Content PubMed PubMed Citation Articles by Kullmann, F. A. Articles by Birder, L. A.

Heterogeneity of muscarinic receptor-mediated Ca²⁺ responses in cultured urothelial cells from rat

Departments of ¹Pharmacology and ²Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania

Submitted 9 July 2007 ; accepted in final form 11 February 2008

Muscarinic receptors (mAChRs) have been identified in the urothelium, a tissue that may be involved in bladder sensory mechanisms. This study investigates the expression and function of mAChRs using cultured urothelial cells from the rat. RT-PCR established the expression of all five mAChR subtypes. Muscarinic agonists acetylcholine (ACh; 10 µM), muscarine (Musc; 20 µM), and oxotremorine methiodide (OxoM; 0.001–20 µM) elicited transient repeatable increases in the intracellular calcium concentration ([Ca²⁺]_i) in 50% of cells. These effects were blocked by the mAChR antagonist atropine methyl nitrate (10 µM). The sources of [Ca²⁺]_i changes included influx from external milieu in 63% of cells and influx from external milieu plus release from internal stores in 27% of cells. The use of specific agonists and antagonists (10 µM M₁ agonist McN-A-343; 10 µM M₂, M₃ antagonists AF-DX 116, 4-DAMP) revealed that M₁, M₂, M₃ subtypes were involved in [Ca²⁺]_i changes. The PLC inhibitor U-73122 (10 µM) abolished OxoM-elicited Ca²⁺ responses in the presence of the M₂ antagonist AF-DX 116, suggesting that M₁, M₃, or M₅ mediates [Ca²⁺]_i increases via PLC pathway. ACh (0.1 µM), Musc (10 µM), oxotremorine sesquifumarate (20 µM), and McN-A-343 (1 µM) acting on M₁, M₂, and M₃ mAChR subtypes stimulated ATP release from cultured urothelial cells. In summary, cultured urothelial cells express functional M₁, M₂, and M₃ mAChR subtypes whose activation results in ATP release, possibly through mechanisms involving [Ca²⁺]_i changes.

bladder; Fura-2 calcium imaging; ATP