Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.1.1.7 (acetylcholinesterase)
28,390 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Unexpectedly, it was observed that the P2-purinoceptor antagonist, suramin (10 microM to 1 mM), reversed the muscle paralysis caused by structurally unrelated non-depolarizing relaxants. Suramin competitively reversed the blocking action of pancuronium. Both the pre- and postsynaptic blockade of nicotinic receptors by pancuronium was counteracted, as shown by the action of suramin, using train-of-four stimulation. Suramin did not affect the paralysis caused by the depolarizing relaxant, succinylcholine. The reversal action of suramin was not due to an increase in the acetylcholine concentration in the synaptic cleft, since neither the contraction of preparations partially paralysed by diminished acetylcholine release in the presence of low Ca2+ or high Mg2+ nor acetylcholinesterase activity were affected. Suramin did not affect the reduction in twitch tension caused by adenosine and potentiated the ATP-induced reduction in twitch, indicating that ATP-sensitive receptors are not involved in the reversal action of suramin. Consequently, these results suggest that the action of suramin is due to binding with a site on the acetylcholine receptor also occupied by non-depolarizing relaxants, but different from the site occupied by succinylcholine.
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PMID:Suramin reverses non-depolarizing neuromuscular blockade in rat diaphragm. 132 40

Within the substantia nigra acetylcholinesterase has non-cholinergic actions that can be demonstrated at both behavioural and cellular levels: the aim of this study was, thus, to explore, in the in vitro guinea pig substantia nigra, the ionic mechanisms which mediate these non-classical phenomena. Acetylcholinesterase had a reversible hyperpolarizing action, via an opening of potassium channels, on a selective population of nigral neurons. These neurons could be identified by an ability to generate bursts of action potentials and by a sensitivity to either amphetamine or to a reduction of glucose in the perfusing medium. The acetylcholinesterase-induced hyperpolarization could not be attributed to a contaminant in the exogenous solution, since a highly purified preparation was even more potent. Furthermore, enzymatic action of any kind could be eliminated as boiled acetylcholinesterase was equally efficacious. The effect of acetylcholinesterase was not subject to tachyphylaxis and was resistant to blockade of potassium channels with tetraethylammonium: since both these phenomena are features of the D2 autoreceptor for dopamine within the substantia nigra, it seems unlikely that acetylcholinesterase is operating on the same target as dendritically released local dopamine. On the other hand, the actions of acetylcholinesterase were enhanced by low glucose and blocked by the sulfonylurea, tolbutamide. These results strongly suggest that acetylcholinesterase can exert a nonenzymatic action and that this action, in the substantia nigra, is mediated by an ATP-sensitive potassium channel.
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PMID:Non-cholinergic effects of acetylcholinesterase in the substantia nigra: a possible role for an ATP-sensitive potassium channel. 135 Sep 99

In vivo age-related changes in membrane fluidity of erythrocytes were investigated by a spin label method after fractionation of the cells by discontinuous density gradient centrifugation. Membrane fluidity was lower in older than in younger erythrocytes in both the normal and diabetic subjects. Cells from diabetic subjects showed a significantly lower level of membrane fluidity for all three age groups (younger, middle and older) than the corresponding cells from normal subjects. The magnitude of progression in the decrease in membrane fluidity in erythrocytes did not differ significantly between both groups of subjects. Both erythrocyte ATP and acetylcholinesterase activity declined, while glycosylated hemoglobin (HbA1c) increased with cell age in both groups of subjects. The HbA1c level in each corresponding fraction was higher in diabetic subjects than normal subjects, but was not correlated with membrane fluidity in either group. Neither the ATP level nor acetylcholinesterase activity in each corresponding fraction differed between groups. Membrane fluidity was significantly correlated with acetylcholinesterase activity in both normal and diabetic subjects. Our results indicate that decreased erythrocyte membrane fluidity in diabetic patients does not form gradually during their life span but develops soon after the cells enter the circulation or during their maturation in the bone marrow.
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PMID:Lowered membrane fluidity of younger erythrocytes in diabetes. 157 26

The orientation of the enzyme Mg(2+)-ATPase (EC 3.6.1.3) in the transverse tubule (TT) membranes of skeletal muscle was investigated using highly purified chicken and rabbit TT vesicles. The percentage of sealed vesicles present in these preparations averaged 88 and 78%, respectively, as calculated from the detergent-induced increase in ouabain-sensitive (Na+, K+)-ATPase activity, ATP-dependent ouabain binding, and lactate dehydrogenase activity (sarcoplasmic enzyme trapped in the TT vesicles). Sidedness of the sealed vesicles, estimated from latency of 5'-nucleotidase, acetylcholinesterase, and adenylate cyclase, was predominantly right-side out (69-76%, chicken TT and 62-70%, rabbit TT). In both chicken and rabbit native vesicles, high Mg(2+)-ATPase activity was detected by addition of ATP to the extravesicular medium; this activity was increased 14-12% by alamethicin pointing to the external localization of the active site. Furthermore, the enzymatic activity resulted partially inhibited by treatment of the chicken TT vesicles with proteinase K or p-hydroxymercuribenzoate. Concanavalin A stimulated 4-fold the chicken TT Mg(2+)-ATPase activity, an effect not potentiated by detergent permeabilization of the intact vesicles, indicating that lectin-binding sites were also solvent accessible. This stimulatory effect was not observed in native or permeabilized rabbit TT vesicles. From these results we conclude that the TT Mg(2+)-ATPase is an ectoenzyme with its nucleotide-hydrolyzing site and glycosylated regions facing the extracellular space. Inhibitors of ion-motive ATPases did not modify the enzyme activity, suggesting a different physiological role for the TT Mg(2+)-ATPase which may be involved in the regulation of muscle fiber functions affected by extracellular ATP levels.
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PMID:Transverse tubule Mg(2+)-ATPase of skeletal muscle. Evidence for extracellular orientation of the chicken and rabbit enzymes. 166 Apr 76

1. Contractile responses and acetylcholine release evoked by nicotine in guinea-pig detrusor strips were determined by isotonic transducer and radioimmunoassay, respectively. Nicotine stimulated acetylcholine release and a contractile response in guinea-pig detrusor strips treated with the cholinesterase inhibitor, methanesulphonyl fluoride (MSF). Both actions evoked by nicotine were antagonized by the nicotinic receptor antagonist, hexamethonium but were insensitive to tetrodotoxin. 2. A sympathetic nerve blocker, guanethidine and a tachykinin antagonist, [D-Arg1, D-Pro2, D-Trp7,9, Leu11]-substance P (rpwwL-SP) partially inhibited the acetylcholine release evoked by nicotine to much the same degree. The inhibitory effects of guanethidine and rpwwL-SP on acetylcholine release were significantly greater than corresponding effects on the contraction evoked by nicotine. 3. In preparations treated with rpwwL-SP to block the tachykinin receptors, guanethidine had no effect on the response to nicotine. Conversely, after treatment with guanethidine to block release of a mediator from sympathetic nerve endings, nicotine-induced responses were not affected by rpwwL-SP. 4. Nicotine-induced contraction was reduced to 30% by the muscarinic cholinoceptor antagonist, atropine and completely abolished after desensitization of P2-purinoceptors with alpha,beta-methylene ATP in the presence of atropine. 5. A concentration-contractile response curve to neurokinin A (NKA) was shifted to the left after cholinesterase inhibition with MSF. Atropine abolished the facilitatory effect of MSF and partially inhibited contractions induced by NKA at 100 nM to 1 microM. The contractile responses to substance P methyl ester (SPOMe) and Tyr0-neurokinin B (Tyr0-NKB) were not influenced by MSF or atropine. 6. After desensitization of NK, tachykinin receptors with SPOMe or preincubation with senktide, the cholinergic component of the nicotine-induced contraction was the same as the control value (100%). 7. Our findings give further support to our previous results: nicotine stimulates acetylcholine release in a tetrodotoxin-resistant manner in guinea-pig bladder and acetylcholine release evoked by nicotine is increased by the coordinated action of sympathetic nerves and tachykinin(s). It is suggested that the tachykinin receptor subtype involved in acetylcholine release is NK,.
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PMID:Contrasting effects of tachykinins and guanethidine on the acetylcholine output stimulated by nicotine from guinea-pig bladder [corrected]. 171 27

In order to define metabolic profiles of smooth muscle cell (SMC) modulation, 16 enzyme activities linked to nucleotide hydrolysis, lipolysis, lysosomal reactivity and intermediate glucose catabolism were compared in four rat arterial models, exhibiting four metabolic phenotypes of modulated smooth muscle cells: (i) "primary synthetic" statein immature aorta; (ii) "contractile" state in adult aorta; (iii) "hypertensive" state in aorta of hypertensive rat, SHR; (iiii) "secondary synthetic" state in diffuse intimal thickening of ligated carotid artery. Contractile SMC presented strong activities of enzymes linked to nucleotide ester hydrolysis and contractility (ATP-A-Ca, ATP-A-Mg, ATP-A-Ca/Mg, 5'nucleotidase) and to lipolytic process (butyryl cholinesterase, acid esterase). These enzyme activities were more pronounced in "hypertensive SMC". Incontrast, the same enzymes were weakly active or not expressed in "synthetic SMC". Increased lysosomal enzyme reactivity was a particular expression of "secondary synthetic SMC". The observed enzyme abnormalities in reactively modulated SMC (proliferative-synthetic phenotype) might be related to the loss of contractility and to the enhanced cell proliferation and lipid accumulation, characteristic features of modulated SMC in atherogenesis.
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PMID:Enzyme histochemical expressions of smooth muscle cell modulation in arterial development, hypertension and remodeling. 193 22

The protein and phospholipid composition of microvesicles released from normal human erythrocytes after ATP depletion, on aging or by treatment with merocyanine 540, dimyristoyl phosphatidylcholine or Ca2+/ionophore A23187 has been compared with the composition of the original cell membrane. It has been shown that these microvesicles are depleted of band 3, glycophorin and phosphatidylinositol 4,5-bisphosphate relative to phospholipid by 40% or more. These data are interpreted to mean that less than half of these membrane components are free to diffuse laterally in the lipid bilayer. Acetylcholinesterase was found to be enriched 2-3-fold in microvesicles, possibly because the removal of non-diffusing proteins from the vesiculating region of the lipid bilayer allows more space for freely diffusing proteins like acetylcholinesterase to enter the microvesicle membrane.
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PMID:Restricted diffusion of integral membrane proteins and polyphosphoinositides leads to their depletion in microvesicles released from human erythrocytes. 217 10

The purpose of this study was to describe changes in the neuromuscular junction of rabbit sartorius muscle after shock by superior mesenteric artery occlusion in 18 rabbits. The results revealed that the numeric and volume densities of the acetylcholine (Ach) vesicles of the sartorius neuromuscular junction were decreased during shock when compared by electron microscopy with normal subjects (p less than .001). We also discovered that the release of lysosomes from hepatic cells, erythrocyte acetylcholinesterase (AchE) activity, and hepatic ATP values decreased during shock. Both scopolamine (0.023 mg/kg) and verapamil (0.74 mg/kg) blocked the release of Ach vesicles and lysosomes, and increased hepatic ATP values. Scopolamine also increased AchE activity. This study shows that the parasympathetic activation plays an important role in mesenteric artery occlusion shock.
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PMID:Morphometric study of neuromuscular junction in rabbits subjected to shock by superior mesenteric artery occlusion. 229 15

About 5% of the total adenylate kinase activity in the rat forebrain was found in a subcellular fraction enriched in synaptic plasma membrane (SPM). The enzyme remained membrane bound after washing by 1M potassium acetate. It was resistant to trypsin digestion under conditions which destroyed 90% of acetylcholinesterase activity. The SPM enzyme was solubilized by 0.25% Triton X-100 resulting in a 4-fold increase in activity. Similar effects were observed when SPM was treated with phospholipases, melittin and trifluoperazine. These results suggest the occurrence of an adenylate kinase closely associated with SPM the activity of which can only be fully expressed by disturbances to the hydrophobic lipid bilayer. The enzyme can be seen as strategically located to play a role in regenerating ATP required for the manifold activities of the synaptic membrane.
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PMID:Evidence for a synaptic plasma membrane associated adenylate kinase in the rat brain. 255 31

A three-dimensional reconstruction of high endothelial venules (HE-venules) of an entire mouse lymph node is presented. The reconstruction has been made by means of the histochemical technique for alpha-naphthylacetate esterase. The course of the HE-venules is shown in coherence with lymphocytic aggregates (follicles and unit), which were concomitantly reconstructed. Carbonic anhydrase, glutamate-, and alpha-glycerophosphate dehydrogenase were found in the high endothelia, while calcium-stimulated NA+, K+ ATP-ase and the acetylcholinesterase were localized to the endothelia and/or to the perivascular sheath of the HE-venules and submarginal capillaries.
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PMID:A three-dimensional reconstruction of high endothelial venules in the mouse lymph node: an enzyme-histochemical study. 293 5


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