Functional role of muscarinic M<sub>2</sub> receptors in <i>α,β</i>‐methylene ATP induced, neurogenic contractions in guinea‐pig ileum

Sawyer, Gregory W.; Lambrecht, Günter; Ehlert, Frederick J.

doi:10.1038/sj.bjp.0703180

Cited by 17 publications

(8 citation statements)

References 25 publications

(47 reference statements)

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“…Contractions were elicited to single doses of αβmeATP in rat vas deferens (in the presence of 6 µM indomethacin) or guinea-pig ileum (in the presence of 70 nM physostigmine) and to ADPβS in ileum (in the presence of 300 nM atropine) leaving 15-60 min before the next dose of agonist was added. The agonists were washed out after responses had peaked (Kennedy and Humphrey 1994;Lambrecht et al 1999Lambrecht et al , 2000aLambrecht et al , 2000bSawyer et al 2000). Ecto-nucleotidase activity of folliculated Xenopus laevis oocytes was studied by measuring spectrophotometrically the production of inorganic phosphate (P i ) from the breakdown of extracellular ATP (100 µM in 0.25 ml Ringer-HEPES solution; 20°C, pH 7.4; Lambrecht et al 2000b).…”

Section: Methodsmentioning

confidence: 99%

NF449: a subnanomolar potency antagonist at recombinant rat P2X 1 receptors

Braun

Rettinger

Ganso

et al. 2001

Naunyn-Schmiedeberg's Archives of Pharmacology

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Antagonistic effects of the novel suramin analogue 4,4',4",4"'-(carbonylbis(imino-5,1,3-benzenetriylbis(carbonylimino)))tetrakis-benzene-1,3-disulfonic acid (NF449) were studied on contractions of the rat vas deferens elicited by alpha,beta-methylene ATP (alphabetameATP; mediated by P2X1 receptors), contractions of the guinea-pig ileal longitudinal smooth muscle elicited by alphabetameATP (mediated by P2X3 receptors) or adenosine 5'-O-(2-thiodiphosphate) (ADPbetaS; mediated by P2Y1 receptors), ATP-induced increases of [Ca2+]i in human embryonic kidney (HEK) 293 cells (mediated by P2Y2 receptors), inward currents evoked by ATP in follicle cell-free Xenopus laevis oocytes expressing rP2X1 or rP2X3 receptors and degradation of ATP by ecto-nucleotidases in folliculated Xenopus laevis oocytes. In addition, NF449 was examined for its P2 receptor specificity in rat vas deferens (alpha1A-adrenoceptors) and guinea-pig ileum (histamine H1 and muscarinic M3 receptors). At native (pIC50=7.15) and recombinant (pIC50=9.54) P2X1 receptors, NF449 was a highly potent antagonist. The P2X3 receptors present in guinea-pig ileum (pIC50=5.04) or expressed in oocytes (pIC50 approximately 5.6) were much less sensitive for NF449. It also was a very weak antagonist at P2Y1 receptors in guinea-pig ileum (pIC50=4.85) and P2Y2 receptors in HEK 293 cells (pIC50=3.86), and showed very low inhibitory potency on ecto-nucleotidases (pIC50<3.5). NF449 (100 microM) did not interact with alpha1A-adrenoceptors or histamine H1 and muscarinic M3 receptors. Thus, the antagonism by NF449 is highly specific for P2 receptors. In conclusion, the subnanomolar potency at rP2X1 receptors and the rank order of potency, P2X1 >> P2X3 > P2Y1 > P2Y2 > ecto-nucleotidases, make NF449 unique among the P2 receptor antagonists reported to date. NF449 may fill the long-standing need for a P2X1-selective radioligand.

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Section: Methodsmentioning

confidence: 99%

NF449: a subnanomolar potency antagonist at recombinant rat P2X 1 receptors

Braun

Rettinger

Ganso

et al. 2001

Naunyn-Schmiedeberg's Archives of Pharmacology

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“…We have shown that acetylcholine-mediated desensitization of histamine-induced contractions is inhibited by pertussis toxin treatment . We have shown that pertussis toxin treatment inhibits a variety of M 2 responses in smooth muscle without inhibiting those of the M 3 receptor (Thomas and Ehlert, 1994;Ostrom and Ehlert, 1999;Sawyer et al, 2000;Ehlert et al, 2001). We have also shown that acetylcholinemediated heterologous desensitization of histamine-induced contractions in the guinea pig ileum is prevented by selective inactivation of M 3 muscarinic receptors with 4-DAMP mustard .…”

Section: Discussionmentioning

confidence: 99%

Muscarinic Agonist-Mediated Heterologous Desensitization in Isolated Ileum Requires Activation of Both Muscarinic M2 and M3 Receptors

Griffin

Matsui

Shehnaz

et al. 2004

The Journal of Pharmacology and Experimental Therapeutics

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We investigated the subtypes of the muscarinic receptor mediating short-term heterologous desensitization in the isolated ileum. Treatment of the ileum from C57BL/6 mice with acetylcholine (30 M) for 20 min caused a subsequent decrease in contractile sensitivity to both prostaglandin F 2␣ (PGF 2␣ ) and the muscarinic agonist, oxotremorine-M. This subsensitivity was characterized by 7-and 3-fold increases in the EC 50 values of the agonists, respectively, with no significant effect on the maximal response. The subsensitivity to PGF 2␣ was prevented in both M 2 and M 3 muscarinic receptor knockout mice. Similarly, the subsensitivity to oxotremorine-M was prevented in M 2 knockout mice. Acetylcholine-mediated desensitization of histamine-induced contractions in the guinea pig ileum was inhibited by both M 2 -and M 3 -selective muscarinic antagonists with high potency, although careful analysis of the data suggested behavior more consistent with an M 2 antagonistic profile. Modeling studies showed that the competitive antagonism of response contingent upon activation of two receptor subtypes should exhibit a pharmacological profile similar to that of the least sensitive signaling pathway. Our results demonstrate that muscarinic agonist-mediated short-term heterologous desensitization of intestinal smooth muscle is contingent upon activation of both M 2 and M 3 muscarinic receptors and that activation of either receptor by itself is insufficient to cause desensitization.It has long been known that the sensitivity of gastrointestinal smooth muscle to the contractile effects of muscarinic agonists decreases after incubation of the tissue with moderate to high concentrations of agonist for relatively short periods (i.e., 5-30 min) (Cantoni and Eastman, 1946;Dale, 1958;Paton, 1961). The mechanism for this short-term desensitization seems to be at a locus downstream from the muscarinic receptor because muscarinic agonist-mediated desensitization is characterized by a decrease in sensitivity to other spasmogens as well. Such a generalized subsensitivity is not surprising considering the metabolic costs required to maintain tonic muscle contraction for several minutes. Thus, prolonged contraction caused by continuous exposure to a muscarinic agonist causes a decreased responsiveness of the contractile machinery to subsequent activation by muscarinic as well as other heterologous agents. It seems likely, therefore, that the muscarinic receptor subtypes mediating heterologous desensitization may be the same as those eliciting contraction.In isolated ileum, subtype-selective muscarinic antagonists inhibit the contractile response to agonists in a manner

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“…Most workers agree that this drug causes cholinergic contraction, i.e. activates excitatory motoneurones of the myenteric plexus (Moody & Burnstock 1982; Kennedy & Humphrey 1994; Matsuo et al 1997; Barthó et al 1999; Sawyer et al 2000), while Wiklund & Gustafsson (1988) report that neither scopolamine nor tetrodotoxin affect the contractile effect of α,β‐meATP. Neurochemical experiments have indicated an enhancement of acetylcholine release from the electrically stimulated myenteric plexus by α,β‐meATP (Sperlágh & Vizi 1991).…”

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confidence: 99%

Effects of Acute Administration of and Tachyphylaxis to α,β‐Methylene ATP in the Guinea‐Pig Small Intestine

Benkó

Undi

Wolf

et al. 2005

Basic Clin Pharma Tox

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Abstract:The aim of the present study was to assess the acute motility effects and desensitizing activity of the stable ATP analogue and P 2X purinoceptor agonist a,b-methylene ATP (a,b-meATP) and the effect of a,b-meATP desensitization on nerve-mediated cholinergic responses in the guinea-pig ileum in vitro. It was confirmed that a,b-meATP (1-30 mM) causes neurally-mediated, cholinergic (tetrodotoxin-and atropine-sensitive) longitudinal contractions. These responses were not influenced by the ganglionic blocking drug hexamethonium (50 mM), or a combination of the adrenergic neurone blocking drug guanethidine (3 mM), the opioid receptor antagonist naloxone (0.5 mM) and the nitric oxide synthase inhibitor N Gnitro-L-arginine (L-NOARG; 100 mM), but were strongly reduced or abolished by the P 2 purinoceptor antagonist PPADS (30 mM) or by tachyphylaxis evoked by 10 mM a,b-meATP. The contractile effect of a,b-meATP (3 mM) was moderately inhibited by 10 mM and strongly suppressed by 30 mM of NF 279, an antagonist predominantly affecting P2X 1 purinoceptors, but left uninfluenced by the P2X 5,7 receptor antagonist Brilliant blue G. No relaxant effect of a,b-meATP was detected in the concentration range of 1-30 mM. Tachyphylaxis to a,b-meATP (1-10 mM) caused a moderate inhibition of the cholinergic (atropine-sensitive) contractile response of the ileum to electrical field stimulation (5 Hz for 5 sec.). This reduction was unaltered in the presence of guanethidine, naloxone and L-NOARG. Responses to nicotine (1 or 2 mM) were not reduced by a,b-meATP tachyphylaxis. It is suggested that a,b-meATP-sensitive P 2X purinoceptors are involved in the prejunctional modulation of cholinergic neurotransmission between the myenteric plexus and longitudinal smooth muscle in the guinea-pig small intestine.a,b-Methylene ATP (a,b-meATP) is an analogue of adenosine-5'-triphoshate (ATP) with a greater metabolic stability than the parent compound. Though its spectrum of agonist activity at various purinoceptors is somewhat different from that of ATP itself (Lambrecht 2000 for review) a,b-meATP is one of the traditional drugs used for studying purinergic mechanisms (Ralevic & Burnstock 1998;Lambrecht 2000). In addition to stimulating some subtypes of P 2X purinoceptors, a,b-meATP can induce powerful tachyphylaxis on these receptors, which has been exploited in the identification of endogenous ATP as neurotransmitter, e.g. in the urinary bladder (Ralevic & Burnstock 1998).Our recent work indicated that the P 2 purinoceptor antagonist PPADS and suramin, two P 2 purinoceptor antagonists of limited subtype selectivity reduced cholinergic longitudinal contractions of the guinea-pig small intestine in vitro (Barthó et al. 1997). Several lines of evidence suggest that this effect reflect an involvement of PPADS-and suramin-sensitive P 2 purinoceptors in the mediation/positive modulation of cholinergic contractions, rather than a nonspecific action (Barthó et al. 1997). In the present work we attempt to approach this problem with a,b-meATP tachyphyl...

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Functional role of muscarinic M₂ receptors in α,β‐methylene ATP induced, neurogenic contractions in guinea‐pig ileum

Cited by 17 publications

References 25 publications

NF449: a subnanomolar potency antagonist at recombinant rat P2X 1 receptors

NF449: a subnanomolar potency antagonist at recombinant rat P2X 1 receptors

Muscarinic Agonist-Mediated Heterologous Desensitization in Isolated Ileum Requires Activation of Both Muscarinic M2 and M3 Receptors

Effects of Acute Administration of and Tachyphylaxis to α,β‐Methylene ATP in the Guinea‐Pig Small Intestine

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Functional role of muscarinic M2 receptors in α,β‐methylene ATP induced, neurogenic contractions in guinea‐pig ileum

Cited by 17 publications

References 25 publications

NF449: a subnanomolar potency antagonist at recombinant rat P2X 1 receptors

NF449: a subnanomolar potency antagonist at recombinant rat P2X 1 receptors

Muscarinic Agonist-Mediated Heterologous Desensitization in Isolated Ileum Requires Activation of Both Muscarinic M2 and M3 Receptors

Effects of Acute Administration of and Tachyphylaxis to α,β‐Methylene ATP in the Guinea‐Pig Small Intestine

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Functional role of muscarinic M₂ receptors in α,β‐methylene ATP induced, neurogenic contractions in guinea‐pig ileum