Search results for "choline"

Vesamicol blocks the recovery, by recycling cholinergic electromotor synaptic vesicles, of the biophysical characteristics of the reserve population.

1993

The effect of vesamicol on the ability of recycling cholinergic synaptic vesicles to recover, during a period of post-stimulation rest, the biophysical properties of the reserve pool was studied in prestimulated perfused blocks of the electric organ of the electric ray, Torpedo marmorata, a tissue rich in cholinergic synapses. The effect of the drug was analysed by high-resolution centrifugal density-gradient fractionation in a zonal rotor of the extracted vesicles. The two vesicle fractions were identified by their ATP and acetylcholine content and the recycled vesicles by their acquisition of [3H]acetylcholine derived from [3H]acetate in the perfusate. Vesamicol (10 microM) blocked the up…

Negatively cooperative binding of melittin to neutral phospholipid vesicles

2007

Abstract The association of basic amphipathic peptides to neutral phospholipid membranes is investigated in terms of binding and partition models. The binding of native and modified melittin to egg-yolk phosphatidylcholine vesicles is studied by steady-state fluorescence spectroscopy. The effect of the ionic strength shows an enhancement of the association as the ionic strength increases. After correction for electrostatic effects by the Gouy–Chapman theory, the melittin binding isotherms could be described by a partition model. In terms of conventional binding mechanisms, which do not take into account electrostatic effects, this would correspond to a negative cooperativity. A plausible wa…

Synergistic Interactions between Vitamin A and Vitamin E against Lipid Peroxidation in Phosphatidylcholine Liposomes

1996

Interactions between alpha-tocopherol and all-trans retinol in suppressing lipid peroxidation were studied in a unilamellar liposomal system of phosphatidylcholine from either egg or soybean, in which peroxidation was initiated by the water-soluble azo initiator 2,2-azobis(2-amidino-propane)hydrochloride and peroxidation was measured as production of conjugated diene hydroperoxides. While all-trans retinol alone was poorly effective, the combination of all-trans retinol with alpha-tocopherol caused an inhibition period far beyond the sum of the inhibition periods observed with individual antioxidants, providing evidence of synergistic interactions. Furthermore, the inhibition rate calculate…

A Role for the β1-β2Loop in the Gating of 5-HT3Receptors

2005

Based on theTorpedoacetylcholine receptor structure, Unwin and colleagues (Miyazawa et al., 2003; Unwin, 2005) hypothesized that the transduction of agonist binding to channel gate opening involves a “pin-into-socket” interaction between αV46 at the tip of the extracellular β1-β2loop and the transmembrane M2 segment and M2-M3 loop. We mutated to cysteine the aligned positions in the 5-HT3Aand 5-HT3Bsubunit β1-β2loops K81 and Q70, respectively. The maximal 5-HT-activated currents in receptors containing 5-HT3A/K81C or 5-HT3B/Q70C were markedly reduced compared with wild type. Desensitization of wild-type currents involved fast and slow components. Mutant currents desensitized with only the f…

Efficient, non-toxic anion transport by synthetic carriers in cells and epithelia.

2016

Transmembrane anion transporters (anionophores) have potential for new modes of biological activity, including therapeutic applications. In particular they might replace the activity of defective anion channels in conditions such as cystic fibrosis. However, data on the biological effects of anionophores are scarce, and it remains uncertain whether such molecules are fundamentally toxic. Here, we report a biological study of an extensive series of powerful anion carriers. Fifteen anionophores were assayed in single cells by monitoring anion transport in real time through fluorescence emission from halide-sensitive yellow fluorescent protein. A bis-(p-nitrophenyl)ureidodecalin shows especial…

Acceleration of the AChBP conformational transition using Temperarure Accelerated Molecular Dynamics

2013

Peripheral motor action of glucagon-like peptide-1 through enteric neuronal receptors.

2010

Background Glucagon-like peptide-1 (GLP-1) is a proglucagon-derived peptide expressed in the enteroendocrine-L cells of small and large intestine and released in response to meal ingestion. Glucagon-like peptide-1 exerts inhibitory effects on gastrointestinal motility through vagal afferents and central nervous mechanisms; however, no data is available about a direct influence on the gastrointestinal wall. Our aim was to investigate the effects of GLP-1 on the spontaneous and evoked mechanical activity of mouse duodenum and colon and to identify the presence and distribution of GLP-1 receptors (GLP-1R) in the muscle coat. Methods Organ bath recording technique and immunohistochemistry were …

Relaxation induced by menthol on mouse gastric tone: analysis of action mechanism.

2012

Thermodynamics and kinetics of ion permeation in wild-type and mutated open active conformation of the human α7 nicotinic receptor

2020

Molecular studies of human pentameric ligand-gated ion channels (LGICs) expressed in neurons and at neuromuscular junctions are of utmost importance in the development of therapeutic strategies for neurological disorders. We focus here on the nicotinic acetylcholine receptor nAChR-α7, a homopentameric channel widely expressed in the human brain, with a proven role in a wide spectrum of disorders including schizophrenia and Alzheimer's disease. By exploiting an all-atom structural model of the full (transmembrane and extracellular) protein in the open, agonist-bound conformation we recently developed, we evaluate the free energy and the mean first passage time of single-ion permeation using …

Acetylcholinesterase activity in juvenileCiona intestinalis(Ascidiacea, Urochordata) after exposure to tributyltin

2012

The acetylcholinesterase (AChE) activity has been studied in 4-day post-fertilization juveniles of Ciona intestinalis exposed to tributyltin (TBT) at 10-5 M using the histochemical method of Karnovsky and Roots. Relative to vertebrate tissues and organs, the development of adult form of ascidians is interesting, because the analysis of many nuclear genes indicated that the ascidians are the closest living relatives of the vertebrates. Therefore, toxicity research using different approaches could provide data for comparative studies with vertebrates. AChE is over-expressed under chemical stress and in some diseases of vertebrates. Therefore, AChE is considered a biomarker of environmental co…