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

---

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

Calcium activation of acetylcholine hydrolysis by bovine brain acetylcholinesterase (Acetylcholine hydrolase, EC 3.1.1.7) forms has been analyzed in terms of changes in kinetic constants and thermodynamic activation parameters. De-acetylation was determined to be the major rate-influencing step in acetylcholine hydrolysis by both 60 000- and 240 000-dalton forms of the brain enzyme and 10 mM Ca2+ increased the rate constant for this step (k+3) by approximately 30% for both forms. For the smaller acetylcholinesterase form the effects of Ca2+ on de-acetylation was equivalent to its effect on the overall rate constant (k) and occurred without an effect on pK. In the case of the 240 000-dalton species, the overall rate constant was increased by Ca2+ by 33% at pH 8.0 and 81% at pH 7.25 and involved a pK shift of -0.2 pH units. For both enzyme forms the rate constants for acetylation (k+2) were increased by Ca2+. Thermodynamic analysis suggested that Ca2+ activation of the acetylation step was entropically driven. Differences between the two enzymes forms in terms of Ca2+ appear to result from association of low molecular weight species.
...
PMID:Kinetic analysis of calcium activation of brain acetylcholinesterase forms. 2 Sep 67

The effect of changing extracellular pH (pHe) on the spontaneous activity of neurons in brain slices taken from the ventral layer of the rat medulla oblongata was compared to the response of neurons in dorsal slices. In the ventral medulla, more than 50% of the neurons were excited by H+. These neurons were found just lateral to the pyramidal tract between the root of the hypoglossal nerve and the trapezoid body. In the dorsal medulla, low pHe caused an inhibition of activity in most neurons, although a few were excited. The fact that H+ elicted excitation predominantly in the ventral medullary substrate to respond to pHe changes. Depression of synaptic transmission within the neuronal network in the slice by reducing the [Ca2+]e and increasing the [Mg2+]e altered the nature of responses of neurons to H+: In the ventral medulla, the majority of neurons were inhibited by H+, whereas in the dorsal medulla more than 50% of neurons were excited. Therefore, "specificity" of the ventral medullary neurons seemed to be dependent upon intact synaptic connections. A possible role of acetylcholine-acetylcholinesterase system in the response of ventral medullary neurons to H+ is discussed.
...
PMID:Effect of H+ on spontaneous neuronal activity in the surface layer of the rat medulla oblongata in vitro. 2 40

1 A number of criteria for considering adenosine 5'-triphosphate (ATP) as a neurotransmitter in the guinea-pig urinary bladder have been examined. In addition, the effect of tachyphylaxis to ATP on the response to non-adrenergic, non-cholinergic nerve stimulation has been re-examined.2 Quinacrine fluorescence histochemistry revealed a population of nerve fibres, ganglion cells, and nerve bundles in the bladder which were not seen in either the iris or vas deferens, where adrenergic and cholinergic nerves predominate. The distribution and morphology of the quinacrine-positive nerves in the bladder were different from those observed with catecholamine fluorescence and cholinesterase histochemistry, and were unaffected by chemical sympathectomy.3 Release of ATP from the bladder during stimulation of intramural excitatory nerves, in the presence of atropine and guanethidine increased to 3-12 times prestimulation levels. Tetrodotoxin abolished both the contractile response and the increase in ATP release resulting from intramural nerve stimulation. There was no increase in ATP release during contraction resulting from direct muscle stimulation following nerve paralysis with tetrodotoxin.4 Sympathectomy with 6-hydroxydopamine did not affect release of ATP in response to intramural nerve stimulation.5 Release of ATP was dependent on the concentration of calcium ion in the medium.6 Contractions in response to non-adrenergic, non-cholinergic intramural nerve stimulation were closely mimicked by ATP, but not by acetylcholine or histamine.7 Adenosine and dipyridamole reduced the contractions to both ATP and non-cholinergic nerve stimulation.8 2-2'-Pyridylisatogen was not a specific blocker of either ATP or intramural nerve stimulation in the guinea-pig bladder. 2-Substituted imidazolines initiated spontaneous activity making it impossible to assess any blocking action that they may have had.9 Prostaglandins (E(1), E(2) and F(2alpha)) gave weak, slow contractions and an increase in spontaneous activity. Both the response to ATP and non-adrenergic, non-cholinergic nerve stimulation were greatly potentiated in the presence of prostaglandins.10 In the presence of indomethacin the response to non-adrenergic, non-cholinergic nerve stimulation was virtually abolished following desensitization to ATP.
...
PMID:Purinergic innervation of the guinea-pig urinary bladder. 2 86

Longitudinal 50-100 mum-thick frozen sections of muscle are picked up on slides coated with 3% EDTA and after drying are incubated to demonstrate acetylcholinesterase. Subsequent incubation in 0.5% K3Fe(CN)6 is followed by fixation for 30 minutes in formol-calcium or formol-saline. After washing, the slides are incubated in 20% aqueous AgNO3 containing 0.1% CuSO4 for 2-30 minutes at 37 C. Following development in a 1% solution of quinol (w/v) 5% with respect to NaSO3 (w/v), axons and subneural apparatus stain dark brown to black in contrast to the less well stained muscle fibers and nuclei. This procedure permits study of the pattern of neuromuscular innervation in skeletal muscle 3 1/2-4 hours after receipt of a sample, and makes possible determination of the terminal innervation ratio.
...
PMID:A rapid method for demonstrating skeletal muscle motor innervation in frozen sections. 5 7

The stomach, intestine and uterus were contracted by PGE1. Stimulating effects of ACh and serotonin were augmented in some of these organs, especially in guinea pig uterus. ACh- and serotonin-induced bronchial contraction, however, decreased after administration of PGE1. Bronchial relaxation induced by adrenaline or noradrenaline was unaffected or increased. Antiadrenergic effects were not detected in the organs tested. ACh-induced contractions of frog rectus abdominus was augmented by PGE. The potentiating effect of PGE1 was almost the same in degree as that of physotigmine, although cholinesterase inhibitory effect was not detected in PGE1. Intravenous injection of PGE1 (10 mug/kg) into rabbits caused a relaxation of the intestine, which was contrary to the result with the isolated organ. Administration of PGE1 (1 mug/100 g, i.p. or 0.1, 1 mug/100 g, i.v.) did not show any curative effects on intestinal paralysis in cecectomized rats. The mechasism of action of PGE1 on rat uterus was found to be calcium-dependant.
...
PMID:[Effect of prostaglandin E1 on the isolated stomach, small intestine, bronchus and uterus of experimental animals and its intestinal effect in vivo]. 12 77

The effects of acute (10 mg/kg) and chronic 10 mg/kg for 30 days) administration of delta-9-tetrahydrocannabinol (delta9-THC) have been studied histochemically in the rat adrenal medulla, which include total catecholamines, noradrenaline, histometric measurements of adrenal medullary areas, calcium content of the medullary cells along with adenosine triphosphatase (ATPase), acetyl cholinesterase (AChE) and butyryl cholinesterase (BChE) activities. Acute delta9-THC treatment reduced the total catecholamine content (including noradrenaline) of the gland, was accompanied by increased ATP-ase, AChE, BChE activities and increased calcium distribution in the gland. Chronic delta9-THC treatment caused significant hypertrophy of the chromaffin tissue, with decreased total catecholamine content, although noradrenaline containing areas exhibited no notable change. The calcium content and ATPase activity were increased along with a concomitant increase in AChE and BChE activities. Although the changes in adrenal medullary enzyme activities following both acute and chronic delta9-THC treatment are qualitatively similar, marked quantitative increase is noted in the chronically treated groups. The results indicate an increased total catecholamine releasing activity of the adrenal medulla following acute delta9-THC treatment, while chronic delta9-THC administration produces a preferential release of adrenaline.
...
PMID:Changes in rat adrenal medulla following delta9-tetrahydrocannabinol treatment. A histochemical study. 12 28

A study in the enzymatic properties of muscle membranes established that sarcolemma of the rabbit skeletal muscles contains the Ca2+-ATPase system which does not require Mg2+ for manifestation of ions activity. By some kinetic properties it differs from ATPase of myosin. The complex Ca-ATP2+ is a substrate of Ca2+-ATPase. Ions of a series of bivalent metals inhibit the latter as well as the passive transport of Ca2+, that may evidence for a definite relation of Ca2+-ATPase with Ca+2 transport in skeletal muscles. Acetyl cholinesterase and AMP-aminohydrolase are strongly bound with the sarcolemma. The sarcolemma structural organization is shown to play a certain role in manifestation of their activity. On the basis of the data obtained when studying the activity in the ATPase systems and dynamics of formation and decay of the intermediate phosphorylated product in the microsomal fraction of cow and rabbit myometrium certain peculiarities are established for the active mechanisms of Ca2+ transport in smooth muscles. A problem is under discussion on the possible active participation of sarcolemma in regulation of Ca2+ concentration in the smooth muscle cells. Two ATPase systems, Mg2+-dependent and Mg2+-dependent Ca2+ activated are found in nuclei; the role of lipids of the skeletal muscles in manifestation of their activity is studied. AMP-amino hydrolase properties are characterized for different areas of the sarcoplasmatic reticulum membranes. The model of E-avitaminous muscular distrophy was used to show disturbances in the structure of sarcolemma and membranes of the sarcoplasmatic reticulum which are accompanied by changes in their ATPase and Ca2+-transporting properties.
...
PMID:[Enzymatic properties in muscle membranes]. 12 74

A simple, reproducible method for the separation of human erythrocytes, described recently (Murphy, J. R. (1973) J. Lab. Clin. Med. 82, 334-341) has been utilized for the purpose of obtaining a wide range of biochemical data on these cells. Using phthalate ester density centrifugation of the fractions obtained by Murphy's method, we established that the cells were separated exclusively on the basis of their densities. Data on a wide range of biochemical and hematological parameters, when compared with previously reported density separation procedures showed that this simple technique can be used to fractionate the cells according to their densities (age) in their own plasma. Cells of increasing density consistently and reproducibly exhibited an increase in hemoglobin concentration, a moderate elevation in Na+ and a decrease in the following: K+, acetylcholinesterase, sialic acid, membrane protein, 2,3-diphosphoglycerate, ATP, cholesterol, phospholipid, mean corpuscular volume and critical hemolytic volume, However, no change in mean corpuscular hemoglobin was evident. The observed differences were not artifacts of the centrifugation process. This was determined in recentrifuged top fractions from which new top and bottom cells were obtained. The latter cells resembled the top fraction from which they were obtained, rather than the original bottom fraction. Whereas the parameters mentioned above exhibited consistency and reproducibility, such was not the case with the ATPase values. Depending on the cell density group examined and/or buffer as well as other conditions, significant variability in the activity levels of the ouabain sensitive, as well as the Ca2+ -stimulated ATPase, was observed. Use of these enzyme activities as indicators of cell age must be viewed with caution.
...
PMID:Biochemical characterization of density-separated human erythrocytes. 12 56

The influence of cholesterol on the membrane-bound acetylcholinesterase and (Ca2+ + Mg2+)-ATPase was studied in erythrocytes of five groups of male rats fed different fat-supplemented diets. Two groups of rats were fed essential fatty acid (EFA) sufficient diets with 5% lard or corn oil as the dietary fat, and two groups were fed EFA-deficient diets: a basic, fat-free diet and the same diet supplemented with 5% hydrogenated beef fat. One additional group of rats was fed a stock diet. The kinetic changes recorded were in the degree of the cooperativity of the inhibition by F- of the acetylcholinesterase and the activation by Ca2+, and by Mg2+ of the (Ca2+ + Mg2+)-ATPase. The kinetic behavior of the enzymes was only modified by cholesterol feeding when they were bound to a membrane with a high fatty acid fluidity (e.g. derived from rats fed the corn oil-supplemented diet). The enzymes from a membrane with a low fatty acid fluidity (e.g. derived from rats fed a lard-supplemented diet) were not altered by cholesterol feeding. The changes were noticeable after 24 hours of cholesterol feeding. It is suggested that the in vivo cholesterol sites are involved in a regulatory mechanism for mammalian membrane-bound enzymes.
...
PMID:Kinetic modifications of the acetylcholinesterase and (Ca2+ + Mg2+)-ATPase in rat erythrocytes by cholesterol feeding. 13 2

The effects of ionic strength, urea, calcium and fluorine ions, ouabain and cholinesterase inhibitors on the changes in the ionization equilibrium of an erythrocyte suspension under heating were studied. Proton release by erythrocytes was compared to a release of potassium ions and hemoglobin from the cells. The proton release under heating is mainly determined by the physico--chemical properties of superficial structures of erythrocytes and does not depend on the activity of cholinesterase, ATPase and glycolytic processes.
...
PMID:[Changes in the ionization equilibrium of erythrocyte suspension under heating]. 13 48


1 2 3 4 5 6 7 8 9 10 Next >>

---