Search results for "choline"

Characterization of prejunctional muscarinic autoreceptors in the guinea-pig trachea

1991

1. The effects of ten muscarinic antagonists on electrically evoked [3H]-acetylcholine release and muscle contraction were compared in an epithelium-free preparation of the guinea-pig trachea that had been preincubated with [3H]-choline. 2. The M3-selective antagonists UH-AH 37, 4-diphenyl-acetoxy-N-piperidine methobromide and para-fluorohexahydrosiladiphenidol were more potent in reducing the contractile response than in facilitating the evoked [3H]-acetylcholine release. Hexahydrosiladiphenidol did not discriminate between pre- and postjunctional effects. The rank order of the postjunctional potencies of the ten antagonists as well as the postjunctional pA2 values obtained for hexahydrosi…

Inhibitory and excitatory muscarinic receptors modulating the release of acetylcholine from the postganglionic parasympathetic neuron of the chicken …

1992

The effects of muscarinic receptor antagonists on ACh release were studied in the absence or presence of cholinesterase (ChE) inhibition using the isolated perfused chicken heart. Presynaptic inhibitory muscarinic autoreceptor were characterized by determining the potency of various antagonists to enhance [3H]-ACh release evoked by field stimulation (3 Hz, 1 min). The order of potencies was: (±)-telenzepine > atropine > 4-DAMP > silahexocyclium > pirenzepine > hexahydro-siladifenidol > AF-DX 116. The comparison with known pA2 values for M1-, M2- and M3-receptors revealed that the presynaptic autoreceptor meets the criteria of an M1-receptor. Basal, not electrically evoked overflow of unlabe…

Increase by NO synthase inhibitors of acetylcholine release from guinea-pig myenteric plexus

1994

The effects of nitric oxide (NO) synthase inhibitors on the electrically evoked release of [3H]acetylcholine were studied in guinea-pig myenteric plexus preparations preincubated with [3H]choline. NG-monomethyl-L-arginine (EC50 5.3 mumol l-1) and NG-nitro-L-arginine (EC50 1.3 mumol l-1) concentration-dependently increased the evoked release of [3H]acetylcholine without affecting the basal outflow. The facilitatory effect of NG-mono-methyl-L-arginine was prevented by L-arginine but not by D-arginine. The results suggest that endogenous NO inhibits the depolarisation-evoked release of acetylcholine.

Choline inhibits acetylcholine release via presynaptic muscarine receptors

1981

The effect of exogenous choline on the outflow of 3H-acetylcholine evoked by field stimulation was studied on the myenteric plexus-longitudinal muscle preparation of the guinea pig. Choline at concentrations of 100 microM and higher depressed the evoked outflow of 3H-acetylcholine in a concentration-dependent manner. The EC50 for the inhibitory action was 300 microM. Scopolamine (10 nM) antagonized the effect of choline which indicates that the inhibition of 3H-acetylcholine outflow is mediated by muscarine receptors. The findings imply that choline at high concentrations does not improve cholinergic synaptic neurotransmission in tissues that are endowed with presynaptic muscarine receptors…

Two types of neuronal muscarine receptors modulating acetylcholine release from guinea-pig myenteric plexus

1985

Longitudinal muscle strips of the guinea-pig ileum were incubated with [3H]choline and the effects of muscarinic agonists on smooth muscle contraction and on spontaneous and electrically-evoked outflow of tritium were studied. Muscarine and pilocarpine concentration-dependently increased both muscle contraction and spontaneous outflow of [3H]ACh, and inhibited the electrically-evoked outflow of [3H]ACh. The increase in spontaneous outflow was prevented by tetrodotoxin and scopolamine, but not by hexamethonium. Oxotremorine (1-100 microM) did not increase the spontaneous outflow of tritium. Pirenzepine in concentrations of 10 and 100 nM hardly affected the muscle contractions induced by pilo…

Release of [3H]acetylcholine from the isolated rat or guinea-pig trachea evoked by preganglionic nerve stimulation; a comparison with transmural stim…

1991

Basal and stimulated outflow of radioactive acetylcholine, phosphorylcholine and choline from rat and guinea-pig isolated tracheae were measured by reverse phase HPLC followed by liquid-scintillation-spectrometry. Tracheae were stimulated either by an electrical field (transmural stimulation) or by a local stimulation of the innervating parasympathetic nerves (preganglionic stimulation). Epithelium was removed in most experiments, as the epithelium inhibits acetylcholine release. The basal tritium efflux (1,600 dpm/3min) from rat isolated tracheae incubated with [3H]choline consisted of 56% [3H]phosphorylcholine and 38% [3H]choline. Preganglionic stimulation (15 Hz, 1,200 pulses) caused a 2…

Immunochemical characterization of anti-acetylcholine receptor antibodies in primary biliary cirrhosis

1988

Although the presence of anti-mitochondrial antibodies is the main characteristic of primary biliary cirrhosis (PBC), other autoantibodies have been described in this disease. This study employs immunoblot methods to test whether the sera of PBC patients also contain antibodies directed against nicotinic acetylcholine receptors (AChR). We show that the majority of patients' sera indeed react with AChR just as sera of myasthenic patients do. In contrast, however, these anti-AChR antibodies do not lead to significant clinical symptoms of myasthenia. In all cases studied, PBC sera recognized a protein with the molecular weight of the alpha-chain of acetylcholine receptor (40 kDa). In addition,…

Habenular effect on hippocampal excitability is not cholinergically-mediated.

1989

Muscarinic Receptor Activation Increases Efflux of Choline from Isolated Heart and Rat Cortex in Vivo. Interactions with Forskolin and IBMX

1986

Muscarinic receptor activation modulates functions of the heart and neurotransmission in the peripheral and central nervous system. Moreover, muscarinic agonists produce changes in the metabolism of, for example, heart tissue, such as inhibition of beta-adrenoceptor-mediated cAMP accumulation, glycogenolysis and lipase activation.

Acetylcholine mediates the release of IL-8 in human bronchial epithelial cells by a NFkB/ERK-dependent mechanism

2007

Acetylcholine may play a role in cell activation and airway inflammation. We evaluated the levels of both mRNA and protein of muscarinic M(1), M(2), M(3) receptors in human bronchial epithelial cell line (16HBE). 16HBE cells were also stimulated with acetylcholine and extracellular signal-regulated kinase1/2 (ERK1/2) and NFkB pathway activation as well as the IL-8 release was assessed in the presence or absence of the inhibitor of Protein-kinase (PKC) (GF109203X), of the inhibitor of mitogenic activated protein-kinase kinase (MAPKK) (PDO9805), of the inhibitor of kinaseB-alpha phosphorilation (pIkBalpha) (BAY11-7082), and of muscarinic receptor antagonists tiotropium bromide, 4-Diphenylacet…