1,721,140 research outputs found
Reconstituition of functional muscarinic receptors by coexpression of amino and carboxyl terminal receptor fragments
No full textFunctional role of proline and tryptophan residues highly conserved among G protein-coupled receptors studies by mutational analysis of the m3 muscarinic receptor
No full textCoexpression studies with mutant muscarinic/adrenergic receptors provide evidence for intermolecular “cross-talk” between G-protein-linked receptors
No full textDetermination of Muscarinic Agonist Potencies at M1 and M2 Muscarinic Receptors in a Modified Pithed rat Preparation
No full textDetermination of Muscarinic Agonist Potencies at M1 and M2 Muscarinic Receptors in a Modified Pithed Rat
No full textThe agonistic potencies of (±)muscarine, (±)cis-2-methyl-5-[(dimethylamino)methyl]-1,3 -oxathiolane methiodide (cis-oxathiolane) and its two enantiomers were determined at muscarinic M1 and M2 receptors in the pithed rat. In non-pretreated animals, i.v. administration of these agents produced bradycardic effects mediated by cardiac M2 receptors followed by increases in heart rate mediated by M1 receptors in sympathetic ganglia. As these responses have been shown to partly overlap, "true" M1 and M2 potencies were determined after selective blockade of M1 and M2 receptors by pirenzepine and methoctramine, respectively. A similar rank order of agonist potencies was obtained at M1 and M2 receptors: (+)cis-oxathiolane > (±)cis-oxathiolane > (±)muscarine > (-)cis-oxathiolane. At both receptor subtypes, (+)cis-oxathiolane was considerably more potent (ca. 30-lold) than its corresponding (-) enantiomer indicating that the agonist binding sites of the two receptor subtypes may have similar stereochemical properties. While (±)muscarine showed similar potencies at M1 and M2 receptors, racemic cis-oxathiolane and its two enantiomers showed a slight selectivity (3 - 7 fold) for M1 receptors indicating the potential usefulness of these compounds in the development of selective M1 receptor agonists
Acetylcholine modulates cortical synaptic transmission via different muscarinic receptors, as studied with receptor knockout mice
No full textThe central cholinergic system plays a crucial role in synaptic plasticity and spatial attention; however, the roles of the individual cholinergic receptors involved in these activities are not well understood at present. In the present study, we show that acetylcholine (ACh) can facilitate or depress synaptic transmission in occipital slices of mouse visual cortex. The precise nature of the ACh effects depends on the ACh concentration, and is input specific, as shown by stimulating different synaptic pathways. Pharmacological blockade of muscarinic receptor (mAChR) subtypes and the Use of M-1-M-5 mAChR-deficient mice showed that specific mAChR subtypes, together with the activity of the cholinesterases (ChEs), mediate facilitation or depression of synaptic transmission. The present data suggest that local ACh, acting through mAChRs, regulates the cortical dynamics making cortical circuits respond to specific stimuli
Beta-cell M 3 muscarinic acetylcholine receptors as potential targets for novel antidiabetic drugs
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Multiple residues in the second extracellular loop are critical for M-3 muscarinic acetylcholine receptor activation
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