The role of M 2-muscarinic receptors in mediating contraction of the pig urinary bladder in vitro

Tomonori Yamanishi, Christopher R. Chapple, Kosaku Yasuda, Russell Chess-Williams

Research output: Contribution to journalArticleResearchpeer-review

67 Citations (Scopus)

Abstract

1. In urinary bladder, M 2-muscarinic receptors predominate, but it is the smaller population of M 3-receptors which mediate detrusor contraction. This study examines the M 2: M 3 ratio and the role of M 2-receptors in contraction of pig urinary bladder. 2. Competition experiments with [ 3H]-QNB determined the ratio of M 2:M 3. In functional studies, affinity values (pK(B)) for 4-DAMP, darifenacin and methoctramine were calculated. Similar experiments were performed on tissues following selective M 3-inactivation (incubation with 40 nM 4-DAMP mustard in the presence of 1 μM methoctramine to protect M 2-receptors), precontraction with 50 mM KCl and relaxation with isoprenaline (30 μM) or forskolin (1 μM). 3. In competition binding, displacement of [ 3H]-QNB by 4-DAMP, darifenacin and methoctramine best fitted a two-site model suggesting a predominant (70-80%) population of M 2-receptors. 4. On normal detrusor in vitro, 4-DAMP and methoctramine caused surmountable antagonism of responses to carbachol with pK(B) values of 9.37±0.07 and 6.05±0.05 respectively. Darifenacin caused unsurmountable antagonism, the apparent pK(B) value being 8.61±0.10. 5. In tissues where the M 3-receptors had been inactivated and cyclic AMP levels elevated, 4-DAMP and darifenacin were less potent, with apparent pK(B) values of 8.72±0.08 and 6.74±0.07. In contrast, methoctramine was more potent, the apparent pK(B) value increasing significantly to 6.86±0.06. 6. These data suggest that the pig bladder possesses a similar muscarinic receptor population to the human bladder and that the M 3-receptor subtype mediates contraction of the normal detrusor muscle. However an involvement of M 2-receptors in contraction can be observed following pharmacological manipulation of the receptor population.

Original languageEnglish
Pages (from-to)1482-1488
Number of pages7
JournalBritish Journal of Pharmacology
Volume131
Issue number7
DOIs
Publication statusPublished - 2000
Externally publishedYes

Fingerprint

Muscarinic Receptors
Urinary Bladder
Swine
Population
Carbachol
Colforsin
Isoproterenol
Cyclic AMP
methoctramine
In Vitro Techniques
Pharmacology
Muscles
4-diphenylacetoxy-1,1-dimethylpiperidinium
darifenacin

Cite this

Yamanishi, Tomonori ; Chapple, Christopher R. ; Yasuda, Kosaku ; Chess-Williams, Russell. / The role of M 2-muscarinic receptors in mediating contraction of the pig urinary bladder in vitro. In: British Journal of Pharmacology. 2000 ; Vol. 131, No. 7. pp. 1482-1488.
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title = "The role of M 2-muscarinic receptors in mediating contraction of the pig urinary bladder in vitro",
abstract = "1. In urinary bladder, M 2-muscarinic receptors predominate, but it is the smaller population of M 3-receptors which mediate detrusor contraction. This study examines the M 2: M 3 ratio and the role of M 2-receptors in contraction of pig urinary bladder. 2. Competition experiments with [ 3H]-QNB determined the ratio of M 2:M 3. In functional studies, affinity values (pK(B)) for 4-DAMP, darifenacin and methoctramine were calculated. Similar experiments were performed on tissues following selective M 3-inactivation (incubation with 40 nM 4-DAMP mustard in the presence of 1 μM methoctramine to protect M 2-receptors), precontraction with 50 mM KCl and relaxation with isoprenaline (30 μM) or forskolin (1 μM). 3. In competition binding, displacement of [ 3H]-QNB by 4-DAMP, darifenacin and methoctramine best fitted a two-site model suggesting a predominant (70-80{\%}) population of M 2-receptors. 4. On normal detrusor in vitro, 4-DAMP and methoctramine caused surmountable antagonism of responses to carbachol with pK(B) values of 9.37±0.07 and 6.05±0.05 respectively. Darifenacin caused unsurmountable antagonism, the apparent pK(B) value being 8.61±0.10. 5. In tissues where the M 3-receptors had been inactivated and cyclic AMP levels elevated, 4-DAMP and darifenacin were less potent, with apparent pK(B) values of 8.72±0.08 and 6.74±0.07. In contrast, methoctramine was more potent, the apparent pK(B) value increasing significantly to 6.86±0.06. 6. These data suggest that the pig bladder possesses a similar muscarinic receptor population to the human bladder and that the M 3-receptor subtype mediates contraction of the normal detrusor muscle. However an involvement of M 2-receptors in contraction can be observed following pharmacological manipulation of the receptor population.",
author = "Tomonori Yamanishi and Chapple, {Christopher R.} and Kosaku Yasuda and Russell Chess-Williams",
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The role of M 2-muscarinic receptors in mediating contraction of the pig urinary bladder in vitro. / Yamanishi, Tomonori; Chapple, Christopher R.; Yasuda, Kosaku; Chess-Williams, Russell.

In: British Journal of Pharmacology, Vol. 131, No. 7, 2000, p. 1482-1488.

Research output: Contribution to journalArticleResearchpeer-review

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T1 - The role of M 2-muscarinic receptors in mediating contraction of the pig urinary bladder in vitro

AU - Yamanishi, Tomonori

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N2 - 1. In urinary bladder, M 2-muscarinic receptors predominate, but it is the smaller population of M 3-receptors which mediate detrusor contraction. This study examines the M 2: M 3 ratio and the role of M 2-receptors in contraction of pig urinary bladder. 2. Competition experiments with [ 3H]-QNB determined the ratio of M 2:M 3. In functional studies, affinity values (pK(B)) for 4-DAMP, darifenacin and methoctramine were calculated. Similar experiments were performed on tissues following selective M 3-inactivation (incubation with 40 nM 4-DAMP mustard in the presence of 1 μM methoctramine to protect M 2-receptors), precontraction with 50 mM KCl and relaxation with isoprenaline (30 μM) or forskolin (1 μM). 3. In competition binding, displacement of [ 3H]-QNB by 4-DAMP, darifenacin and methoctramine best fitted a two-site model suggesting a predominant (70-80%) population of M 2-receptors. 4. On normal detrusor in vitro, 4-DAMP and methoctramine caused surmountable antagonism of responses to carbachol with pK(B) values of 9.37±0.07 and 6.05±0.05 respectively. Darifenacin caused unsurmountable antagonism, the apparent pK(B) value being 8.61±0.10. 5. In tissues where the M 3-receptors had been inactivated and cyclic AMP levels elevated, 4-DAMP and darifenacin were less potent, with apparent pK(B) values of 8.72±0.08 and 6.74±0.07. In contrast, methoctramine was more potent, the apparent pK(B) value increasing significantly to 6.86±0.06. 6. These data suggest that the pig bladder possesses a similar muscarinic receptor population to the human bladder and that the M 3-receptor subtype mediates contraction of the normal detrusor muscle. However an involvement of M 2-receptors in contraction can be observed following pharmacological manipulation of the receptor population.

AB - 1. In urinary bladder, M 2-muscarinic receptors predominate, but it is the smaller population of M 3-receptors which mediate detrusor contraction. This study examines the M 2: M 3 ratio and the role of M 2-receptors in contraction of pig urinary bladder. 2. Competition experiments with [ 3H]-QNB determined the ratio of M 2:M 3. In functional studies, affinity values (pK(B)) for 4-DAMP, darifenacin and methoctramine were calculated. Similar experiments were performed on tissues following selective M 3-inactivation (incubation with 40 nM 4-DAMP mustard in the presence of 1 μM methoctramine to protect M 2-receptors), precontraction with 50 mM KCl and relaxation with isoprenaline (30 μM) or forskolin (1 μM). 3. In competition binding, displacement of [ 3H]-QNB by 4-DAMP, darifenacin and methoctramine best fitted a two-site model suggesting a predominant (70-80%) population of M 2-receptors. 4. On normal detrusor in vitro, 4-DAMP and methoctramine caused surmountable antagonism of responses to carbachol with pK(B) values of 9.37±0.07 and 6.05±0.05 respectively. Darifenacin caused unsurmountable antagonism, the apparent pK(B) value being 8.61±0.10. 5. In tissues where the M 3-receptors had been inactivated and cyclic AMP levels elevated, 4-DAMP and darifenacin were less potent, with apparent pK(B) values of 8.72±0.08 and 6.74±0.07. In contrast, methoctramine was more potent, the apparent pK(B) value increasing significantly to 6.86±0.06. 6. These data suggest that the pig bladder possesses a similar muscarinic receptor population to the human bladder and that the M 3-receptor subtype mediates contraction of the normal detrusor muscle. However an involvement of M 2-receptors in contraction can be observed following pharmacological manipulation of the receptor population.

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