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Experientia Sep 1958
Topics: Alkaloids; Muscarine; Parasympathomimetics; Stereoisomerism
PubMed: 13609577
DOI: 10.1007/BF02159151 -
Neuroscience Letters Jan 1991In cultured bullfrog sympathetic neurones, cell-attached patch clamp revealed a voltage-independent K+ channel having a conductance of 46-113 pS at an external K+ of...
In cultured bullfrog sympathetic neurones, cell-attached patch clamp revealed a voltage-independent K+ channel having a conductance of 46-113 pS at an external K+ of 2-120 mM. Muscarine (10-20 microM), applied to the cell membrane outside a recording pipette, increased its open probability and mean open time in an atropine-sensitive manner. This muscarine-activated K+ channel could underlie some of the muscarinic inhibitory postsynaptic potentials in both central and peripheral nervous systems.
Topics: Animals; Atropine; Cell Membrane; Cells, Cultured; Ganglia, Sympathetic; Membrane Potentials; Muscarine; Neurons; Potassium Channels; Rana catesbeiana; Rana pipiens
PubMed: 2020374
DOI: 10.1016/0304-3940(91)90682-j -
Journal of the American Chemical Society Apr 2002The stereoselective synthesis of tetrahydrofurans was achieved by formal [3+2]-cycloaddition of allyl and crotylsilanes with alpha-triethylsilyloxy aldehydes. The scope...
Stereoselective synthesis of tetrahydrofurans via formal [3+2]-cycloaddition of aldehydes and allylsilanes. Formal total synthesis of the muscarine alkaloids (-)-allomuscarine and (+)-epimuscarine.
The stereoselective synthesis of tetrahydrofurans was achieved by formal [3+2]-cycloaddition of allyl and crotylsilanes with alpha-triethylsilyloxy aldehydes. The scope of the reaction was examined by using different alpha-substituted aldehydes and different substituents on the silicon. Tamao oxidation of the products resulted in formation of diols that are easily functionalized allowing an entry to natural products synthesis. The formal total synthesis of the muscarine alkaloids (-)-allomuscarine and (+)-epimuscarine was achieved.
Topics: Aldehydes; Alkaloids; Allyl Compounds; Furans; Magnetic Resonance Spectroscopy; Muscarine; Oxidation-Reduction; Silanes; Stereoisomerism
PubMed: 11929250
DOI: 10.1021/ja012193b -
Comptes Rendus Des Seances de La... 1996Inwardly rectifying muscarinic potassium channels are directly activated by M2 muscarinic receptors in heart via a Pertussis toxin-sensitive G-protein. An intracellular... (Review)
Review
Inwardly rectifying muscarinic potassium channels are directly activated by M2 muscarinic receptors in heart via a Pertussis toxin-sensitive G-protein. An intracellular second messenger is not involved in their activation. These channels undergo rapid (in about 30 seconds) and short-term desensitization. This desensitization is reversible in about 5 minutes. The molecular events underlying muscarinic potassium channels desensitization are still under study and apparently involve a phosphorylation/dephosphorylation process of one the proteins, i.e. the receptor, the G-protein or the channel itself.
Topics: Acetylcholine; Animals; GTP-Binding Proteins; Muscarine; Myocardium; Pertussis Toxin; Potassium Channels; Virulence Factors, Bordetella
PubMed: 8869234
DOI: No ID Found -
Progress in Brain Research 1990
Review
Topics: Acetylcholine; Animals; Hippocampus; In Vitro Techniques; Muscarine; Pyramidal Tracts; Receptors, Cholinergic; Second Messenger Systems; Synaptic Transmission
PubMed: 2176300
DOI: 10.1016/s0079-6123(08)60910-3 -
British Journal of Pharmacology Dec 19761 The affinity of 17 compounds for muscarine-sensitive acetylcholine receptors in atrial pacemaker cells and ileum of the guinea-pig has been measured at 29 degrees C in... (Comparative Study)
Comparative Study
A comparison of affinity constants for muscarine-sensitive acetylcholine receptors in guinea-pig atrial pacemaker cells at 29 degrees C and in ileum at 29 degrees C and 37 degrees C.
1 The affinity of 17 compounds for muscarine-sensitive acetylcholine receptors in atrial pacemaker cells and ileum of the guinea-pig has been measured at 29 degrees C in Ringer-Locke solution. Measurements were also made at 37 degrees C with 7 of them. 2 Some of the compounds had much higher affinity for the receptors in the ileum than for those in the atria. For the most selective compound, 4-diphenylacetoxy-N-methylpiperidine methiodide, the difference was approximately 20-fold. The receptors in the atria are therefore different the structure from those in the ileum. 3 The effect of temperature on affinity are not the same for all the compounds, tested indicating different enthalpies and entropies of adsorption and accounting for some of the difficulty experienced in predicting the affinity of new compounds.
Topics: Acetylcholine; Animals; Guinea Pigs; Heart; Ileum; In Vitro Techniques; Muscarine; Organ Specificity; Receptors, Drug; Temperature; Thermodynamics; Time Factors
PubMed: 1000135
DOI: 10.1111/j.1476-5381.1976.tb08631.x -
Progress in Brain Research 2004
Review
Topics: Acetylcholine; Animals; Cerebral Cortex; Muscarine; Neurotransmitter Agents; Nicotine; Synapses
PubMed: 14650908
DOI: No ID Found -
Psychopharmacology Jan 1979
Topics: Aggression; Animals; Anticonvulsants; Behavior, Animal; Catecholamines; Cats; Dopamine; Drug Interactions; Female; Ganglionic Blockers; Histamine H1 Antagonists; Humans; Injections, Intraventricular; Male; Muscarine; Neuromuscular Blocking Agents; Parasympatholytics; Serotonin Antagonists
PubMed: 34184
DOI: 10.1007/BF00432286 -
Journal of Neurochemistry Sep 2001We characterized changes in membrane currents and the cytosolic Ca(2+) concentration, [Ca(2+)](i), in response to caffeine, and compared them with those in response to...
We characterized changes in membrane currents and the cytosolic Ca(2+) concentration, [Ca(2+)](i), in response to caffeine, and compared them with those in response to muscarine using the perforated patch-clamp technique and fura-2 microfluorimetry in guinea-pig adrenal chromaffin cells. Catecholamine release from single voltage-clamped cells was monitored with amperometry using carbon microelectrodes. Caffeine produced a transient outward current (I(out)) at holding potentials over - 60 mV, increasing in amplitude with increasing the potentials. It also evoked a rapid increase of [Ca(2+)](i) at all potentials examined. The current-voltage relation revealed that the activation of K(+) channels was responsible for the I(out) evoked by caffeine. Both current and [Ca(2+)](i) responses were reversibly abolished by cyclopiazonic acid, an inhibitor of Ca(2+)-pump ATPase. At - 30 mV, the caffeine-induced I(out), but not [Ca(2+)](i), was partly inhibited by either charybdotoxin or apamin. In the majority of cells tested, caffeine induced a larger I(out) but a smaller [Ca(2+)](i) increase than muscarine. Caffeine and muscarine increased catecholamine release from voltage-clamped single cells concomitant with the transient increase of [Ca(2+)](i), and there was a positive correlation between them. These results indicate that caffeine activates Ca(2+)-dependent K(+) channels and catecholamine secretion due to the release of Ca(2+) from internal stores in voltage-clamped adrenal chromaffin cells of the guinea-pig. There seems to be a spatial difference between [Ca(2+)](i) increased by Ca(2+) release from caffeine-sensitive stores and that released from muscarine (inositol 1,4,5-trisphosphate)-sensitive ones.
Topics: Adrenal Glands; Animals; Caffeine; Calcium; Catecholamines; Chromaffin Cells; Cricetinae; Exocytosis; Intracellular Membranes; Male; Muscarine; Muscarinic Agonists; Osmolar Concentration; Patch-Clamp Techniques; Potassium Channel Blockers; Potassium Channels
PubMed: 11579133
DOI: 10.1046/j.1471-4159.2001.00502.x -
The Journal of Pharmacology and... May 1987The M2 subtype of the muscarinic receptor was investigated using the antagonist AF-DX 116. In "in vitro" and "in vivo" experiments, AF-DX 116 behaved as a competitive...
The M2 subtype of the muscarinic receptor was investigated using the antagonist AF-DX 116. In "in vitro" and "in vivo" experiments, AF-DX 116 behaved as a competitive antagonist and exhibited a selectivity for cardiac muscarinic-mediated functions. It antagonized negative chronotropic and inotropic effects exerted by muscarinic receptor activation in the guinea pig atria with an affinity (pA2) 10-fold greater than that estimated in intestinal and tracheal smooth muscle preparations. It also reversed the negative chronotropic effect induced by peripheral vagal stimulation, intrasinus node injection of bethanechol and central vagal activation by clonidine. In all these in vivo functions, AF-DX 116 was approximately 10 times less potent than atropine, while being several hundred-fold less potent in antagonizing acetylcholine-mediated bronchoconstriction and gastric emptying. These results are consistent with the hypothesis that the cardiac muscarinic receptors constitute a subclass of the M2 subtype.
Topics: Animals; Atropine; Bethanechol; Bethanechol Compounds; Carbachol; Cats; Dimethylphenylpiperazinium Iodide; Dogs; Dose-Response Relationship, Drug; Electric Stimulation; Female; Gastric Acid; Gastric Emptying; Guinea Pigs; Heart; Heart Rate; Male; Muscarine; Muscle Contraction; Muscle, Smooth; Myocardial Contraction; Pirenzepine; Rats; Receptors, Muscarinic
PubMed: 2883303
DOI: No ID Found