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The Journal of Clinical Investigation Jul 1976An in vitro system for perifusion of rat pancreatic islets has been utilized to define the effects of epinephrine on acetylcholine-induced insulin release over varying...
An in vitro system for perifusion of rat pancreatic islets has been utilized to define the effects of epinephrine on acetylcholine-induced insulin release over varying concentrations of the two agents. Perifusion of islets with epinephrine before challenge with acetycholine produced marked enhancement of both phases of cholinergically induced insulin release; enhancement of the first phase being more marked with increase in acetylcholine concentration and the converse being observed with the second phase. Perifusion of islets with epinephrine during stimulation with acetylcholine produced inhibition of insulin release, an effect dependent upon the concentration of epinephrine and of acetylcholine. There was an order of difference in the acetycholine concentration needed to overcome significant epinephrine-mediated inhibition of the first phase of insulin release (5 X 10(-4) mug/ml) and that needed to overcome inhibition of the second phase (5 X 10(-3) mug/ml). Comparison of the effects of various concentrations of epinephrine on glucose- and acetyl-choline-induced insulin release revealed that epinephrine was a less potent inhibitor of the first phase of acetylcholine-induced insulin release than of the first phase of glucose-induced insulin release. These data provide some insight into the potential interactions between cholinergic and adrenergic autonomic systems in modifying insulin release.
Topics: Acetylcholine; Animals; Drug Interactions; Epinephrine; Female; Glucose; In Vitro Techniques; Insulin; Male; Rats
PubMed: 932207
DOI: 10.1172/JCI108454 -
Zhongguo Yao Li Xue Bao = Acta... Sep 1982
Topics: Acetylcholine; Animals; Brain Chemistry; Male; Rabbits; Radioimmunoassay
PubMed: 6216724
DOI: No ID Found -
BMC Neurology Oct 2019Brain ischemia activates the parasympathetic cholinergic pathway in animal models of human disease. However, it remains unknown whether activation of the cholinergic...
BACKGROUND
Brain ischemia activates the parasympathetic cholinergic pathway in animal models of human disease. However, it remains unknown whether activation of the cholinergic pathway impacts immune defenses and disease outcomes in patients with ischemic stroke. This study investigated a possible association between peripheral cholinergic activity, post-stroke infection, and mortality.
METHODS
In this study, we enrolled 458 patients with acute ischemic stroke (< 24 h after onset), 320 patients with ischemic stroke on day 10, and 216 healthy subjects. Peripheral cholinergic activity, reflected by intracellular acetylcholine (ACh) content in human peripheral blood mononuclear cells (PBMCs), was determined by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Expression of acetylcholinesterase (AChE) and choline acetyltransferase (ChAT) was measured by quantitative real-time PCR and western blot. Regression analyses were used to assess associations between peripheral cholinergic function and clinical outcomes.
RESULTS
Within 24 h after the onset of acute ischemic stroke, there was a rapid increase in peripheral cholinergic activity that correlated with brain infarction volume (r = 0.67, P < 0.01). Specifically, lymphocyte-derived ACh levels were significantly higher in stroke patients with pneumonia (0.21 ± 0.02 ng/10 PBMC versus 0.15 ± 0.01 ng/10 PBMC, P = 0.03). Of note, lymphocytic AChE catalytic activity was significantly lower in these patients. One-year mortality was significantly greater in patients with higher intracellular ACh levels within the first 24 h after acute stroke.
CONCLUSIONS
Lymphocytes produced increased amounts of ACh in patients with acute stroke, and pneumonia was a likely result. The association between this enhanced cholinergic activity and increased risk of pneumonia/mortality suggests that increased cholinergic activity may contribute to fatal post-stroke infection.
Topics: Acetylcholine; Aged; Brain Ischemia; Female; Humans; Lymphocytes; Male; Middle Aged
PubMed: 31615442
DOI: 10.1186/s12883-019-1481-5 -
Proceedings of the National Academy of... Nov 2007The conformation of the neurotransmitter acetylcholine bound to the fully functional nicotinic acetylcholine receptor embedded in its native membrane environment has...
The conformation of the neurotransmitter acetylcholine bound to the fully functional nicotinic acetylcholine receptor embedded in its native membrane environment has been characterized by using frequency-selective recoupling solid-state NMR. Six dipolar couplings among five resolved (13)C-labeled atoms of acetylcholine were measured. Bound acetylcholine adopts a bent conformation characterized with a quaternary ammonium-to-carbonyl distance of 5.1 A. In this conformation, and with its orientation constrained to that previously determined by us, the acetylcholine could be docked satisfactorily in the agonist pocket of the agonist-bound, but not the agonist-free, crystal structure of a soluble acetylcholine-binding protein from Lymnaea stagnali. The quaternary ammonium group of the acetylcholine was determined to be within 3.9 A of five aromatic residues and its acetyl group close to residues C187/188 of the principle and residue L112 of the complementary subunit. The observed >C O chemical shift is consistent with H bonding to the nicotinic acetylcholine receptor residues gammaY116 and deltaT119 that are homologous to L112 in the soluble acetylcholine-binding protein.
Topics: Acetylcholine; Animals; Binding Sites; Lymnaea; Magnetic Resonance Spectroscopy; Molecular Conformation; Nicotinic Agonists; Receptors, Nicotinic
PubMed: 17989232
DOI: 10.1073/pnas.0704785104 -
The European Journal of Neuroscience Jul 2006Cortical processing is strongly influenced by the actions of neuromodulators such as acetylcholine (ACh). Early studies in anaesthetized cats argued that acetylcholine...
Cortical processing is strongly influenced by the actions of neuromodulators such as acetylcholine (ACh). Early studies in anaesthetized cats argued that acetylcholine can cause a sharpening of orientation tuning functions and an improvement of the signal-to-noise ratio (SNR) of neuronal responses in primary visual cortex (V1). Recent in vitro studies have demonstrated that acetylcholine reduces the efficacy of feedback and intracortical connections via the activation of muscarinic receptors, and increases the efficacy of feed-forward connections via the activation of nicotinic receptors. If orientation tuning is mediated or enhanced by intracortical connections, high levels of acetylcholine should diminish orientation tuning. Here we investigate the effects of acetylcholine on orientation tuning and neuronal responsiveness in anaesthetized marmoset monkeys. We found that acetylcholine caused a broadening of the orientation tuning in the majority of cells, while tuning functions became sharper in only a minority of cells. Moreover, acetylcholine generally facilitated neuronal responses, but neither improved signal-to-noise ratio, nor reduced trial-to-trial firing rate variance systematically. Acetylcholine did however, reduce variability of spike occurrences within spike trains. We discuss these findings in the context of dynamic control of feed-forward and lateral/feedback connectivity by acetylcholine.
Topics: Acetylcholine; Action Potentials; Anesthesia; Animals; Callithrix; Neurons; Normal Distribution; Orientation; Photic Stimulation; Visual Cortex
PubMed: 16882027
DOI: 10.1111/j.1460-9568.2006.04882.x -
Molecular Pharmacology Sep 2009A family of 20 tris-azaaromatic quaternary ammonium (AQA) compounds were tested for their inhibition of alpha7 nicotinic acetylcholine receptors (nAChRs) expressed in...
Selective inhibition of acetylcholine-evoked responses of alpha7 neuronal nicotinic acetylcholine receptors by novel tris- and tetrakis-azaaromatic quaternary ammonium antagonists.
A family of 20 tris-azaaromatic quaternary ammonium (AQA) compounds were tested for their inhibition of alpha7 nicotinic acetylcholine receptors (nAChRs) expressed in Xenopus laevis oocytes. The potency of inhibitory activity was related to the hydrophobic character of the tris head groups. Two tris-AQA compounds were studied in detail: the highly effective inhibitor 1,3,5-tri-[5-(1-quinolinum)-pent-1-yn-1-yl]-benzene tribromide (tPyQB) and the less potent antagonist 1,3,5,-tri-{5-[1-(2-picolinium)]-pent-1-yn-1-yl}benzene tribromide (tPy2PiB). In addition, we evaluated 1,2,4,5-tetra-{5-[1-(3-benzyl)pyridinium]pent-1-yl}benzene tetrabromide (tkP3BzPB), a tetrakis-AQA with very hydrophobic headgroups. We compared the activity of the AQA compounds to the frequently used alpha7-antagonist methyllycaconitine (MLA). Both tPyQB and tkP3BzPB were selective antagonists of alpha7. However, although inhibition by tPyQB was reversible within 5 min, the recovery time constant for tkP3BzPB inhibition was 26.6 +/- 0.8 min, so that the equilibrium inhibition in the prolonged presence of nanomolar concentrations of tkP3BzPB was nearly 100%. The potency, selectivity, and slow reversibility of tkP3BzPB were comparable with or greater than that of MLA. The inhibitory actions of tPyQB, tPy2PiB, and tkP3BzPB were evaluated on the acetylcholine (ACh)-evoked responses of native nAChRs in rat brain slices. The alpha7-mediated responses of hippocampal interneurons were effectively reduced by 1 microM tPyQB and tkP3BzPB but not tPy2PiB. In rat medial septum, tkP3BzPB produced a greater inhibition of ACh-evoked responses of cells with fast inward currents (type I) than of cells with predominantly slow kinetics (type II), suggesting that tkP3BzPB can block alpha7 yet preserve the responsiveness of non-alpha7 receptors. These agents might be helpful in elucidating complex receptor responses in brain regions with mixed populations of nAChRs.
Topics: Acetylcholine; Animals; Neurons; Oocytes; Quaternary Ammonium Compounds; Rats; Receptors, Nicotinic; Xenopus laevis; alpha7 Nicotinic Acetylcholine Receptor
PubMed: 19556356
DOI: 10.1124/mol.109.056176 -
The Journal of General Physiology Nov 1969Transmembrane potentials recorded from the rabbit heart in vitro were displayed as voltage against time (V, t display), and dV/dt against voltage (V, V or phase-plane...
Transmembrane potentials recorded from the rabbit heart in vitro were displayed as voltage against time (V, t display), and dV/dt against voltage (V, V or phase-plane display). Acetylcholine was applied to the recording site by means of a hydraulic system. Results showed that (a) differences in time course of action potential upstroke can be explained in terms of the relative magnitude of fast and slow phases of depolarization; (b) acetylcholine is capable of depressing the slow phase of depolarization as well as the plateau of the action potential; and (c) action potentials from nodal (SA and AV) cells seem to lack the initial fast phase. These results were construed to support a two-component hypothesis for cardiac electrogenesis. The hypothesis states that cardiac action potentials are composed of two distinct and physiologically separable "components" which result from discrete mechanisms. An initial fast component is a sodium spike similar to that of squid nerve. The slow component, which accounts for both a slow depolarization during phase 0 and the plateau, probably is dependent on the properties of a slow inward current having a positive equilibrium potential, coupled to a decrease in the resting potassium conductance. According to the hypothesis, SA and AV nodal action potentials are due entirely or almost entirely to the slow component and can therefore be expected to exhibit unique electrophysiological and pharmacological properties.
Topics: Acetylcholine; Action Potentials; Animals; Heart Conduction System; Membrane Potentials; Rabbits; Time
PubMed: 5346531
DOI: 10.1085/jgp.54.5.607 -
The Journal of Physiology May 2010
Topics: Acetylcholine; Animals; Ion Channel Gating; Ion Channels; Iontophoresis; Kinetics; Models, Statistical; Ranidae; Receptors, Neurotransmitter
PubMed: 20436045
DOI: 10.1113/jphysiol.2010.188664 -
SLAS Discovery : Advancing Life... Dec 2017Matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-MS) offers a label-free alternative for the screening of biochemical targets in both 1536- and...
Matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-MS) offers a label-free alternative for the screening of biochemical targets in both 1536- and 6144-assay formats, as well as potentially providing increased sensitivity, reproducibility, and the simultaneous detection of multiple assay components within a specified m/z range. Ion suppression effects are one of the principal limitations reported for MS analysis. Within MALDI-MS screening, it has been identified that certain biochemical components incorporated into the assay (e.g., the buffers used to preserve the physiological conditions of the enzyme, salts, and other additives) induce suppression of the analyte ion signals monitored. This poorly understood phenomenon of ion suppression is a key reason the screening community has been reluctant to shift their investigations toward MS methods with reduced sample cleanup. Using acetylcholine as an assay substrate mimic, we have generated robust data to quantify the degree to which the most highly used components (base buffers, additional components, detergents, cell culture media, and other additives) within current screening assays are compatible with MALDI-MS. Here, the most suitable buffers and components, along with their identified optimal concentrations in terms of limiting ion suppression effects, are proposed for use in screening assays measured by MALDI-MS.
Topics: Acetylcholine; Buffers; Image Processing, Computer-Assisted; Signal Processing, Computer-Assisted; Software; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
PubMed: 27932699
DOI: 10.1177/1087057116681726 -
Journal of the Royal Society, Interface Mar 2010Many cephalopods exhibit remarkable dermal iridescence, a component of their complex, dynamic camouflage and communication. In the species Euprymna scolopes, the...
Many cephalopods exhibit remarkable dermal iridescence, a component of their complex, dynamic camouflage and communication. In the species Euprymna scolopes, the light-organ iridescence is static and is due to reflectin protein-based platelets assembled into lamellar thin-film reflectors called iridosomes, contained within iridescent cells called iridocytes. Squid in the family Loliginidae appear to be unique in which the dermis possesses a dynamic iridescent component with reflective, coloured structures that are assembled and disassembled under the control of the muscarinic cholinergic system and the associated neurotransmitter acetylcholine (ACh). Here we present the sequences and characterization of three new members of the reflectin family associated with the dynamically changeable iridescence in Loligo and not found in static Euprymna iridophores. In addition, we show that application of genistein, a protein tyrosine kinase inhibitor, suppresses ACh- and calcium-induced iridescence in Loligo. We further demonstrate that two of these novel reflectins are extensively phosphorylated in concert with the activation of iridescence by exogenous ACh. This phosphorylation and the correlated iridescence can be blocked with genistein. Our results suggest that tyrosine phosphorylation of reflectin proteins is involved in the regulation of dynamic iridescence in Loligo.
Topics: Acetylcholine; Amino Acid Sequence; Animals; Color; Genistein; Loligo; Molecular Sequence Data; Phosphorylation; Proteins; Sequence Alignment; Signal Transduction; Skin
PubMed: 19776150
DOI: 10.1098/rsif.2009.0299