Muscarinic Receptor Subtypes and Receptor‐Coupled Phosphatidylinositol Hydrolysis in Rat Bladder Smooth Muscle
Open Access
- 1 November 1997
- journal article
- research article
- Published by Wiley in International Journal of Urology
- Vol. 4 (6), 591-596
- https://doi.org/10.1111/j.1442-2042.1997.tb00315.x
Abstract
Background: The purpose of this study was to evaluate the muscarinic receptor subtypes expressed in rat bladder smooth muscle and characterize the muscarinic receptor‐coupled phosphatidylinositol (PI) hydrolysis in order to clarify the first step of bladder smooth muscle contraction. Methods: Expressions of mRNAs of muscarinic receptor subtypes were examined by Northern blot analysis. Changes in the mass of inositol 1,4,5‐trisphosphate(IP3) and the inhibitory effects of muscarinic subtype specific antagonists on PI hydrolysis were determined after carbachol stimulation. Results: mRNAs of m2 and m3 genes, encoding M2 and M3 receptors, were expressed in rat bladder smooth muscle. Carbachol produced a rapid increase of IP3, which returned to the basal level within 30 seconds. 4‐Diphenylacetoxyl‐N‐methylpiperidine methiodide (4‐DAMP; M1 and M3 antagonist) strongly inhibited the PI hydrolysis, but methoctramine (M2 antagonist) partially inhibited it at 10‐4 mol/L The 1C50 value for atropine was 9.5 times 10‐9 mol/L, for pirenzepine 6.4 times 10‐6 mol/L, and for 4‐DAMP 1.5 times 10‐7 mol/L. Conclusion: M2 and M3 receptors are expressed in rat urinary bladder. Only M3 receptor was involved in the production of IP3, which might induce the initial phase of contractile response in rat bladder smooth muscle after carbachol stimulation.Keywords
This publication has 19 references indexed in Scilit:
- Evaluation of mRNAs Encoding Muscarinic Receptor Subtypes in Human Detrusor MuscleJournal of Urology, 1996
- Effect of Carbachol and Norepinephrine on Phosphatidyl Inositol Hydrolysis and Cyclic Amp Levels in Guinea Pig Urinary TractJournal of Urology, 1995
- Muscarinic Receptors—Characterization, coupling and functionPharmacology & Therapeutics, 1993
- Cloning of the rat m3, m4 and m5 muscarinic acetylcholine receptor genes by the Polymerase Chain Reaction (PCR) and the pharmacological characterization of the expressed genesLife Sciences, 1992
- Molecular pharmacology of muscarinic receptor heterogeneityLife Sciences, 1989
- Amplification of the rat m2 muscarinic receptor gene by the polymerase chain reaction: Functional expression of the M2 muscarinic receptorLife Sciences, 1989
- Mass changes of inositol(1,4,5) trisphosphate in trachealis muscle following agonist stimulationEuropean Journal of Pharmacology, 1989
- Tissue distribution of mRNAs encoding muscarinic acetylcholine receptor subtypesFEBS Letters, 1988
- Differential regulation of PI hydrolysis and adenylyl cyclase by muscarinic receptor subtypesNature, 1988
- A technique for radiolabeling DNA restriction endonuclease fragments to high specific activityAnalytical Biochemistry, 1983