Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.1.8 (cholinesterase)
 12,691 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The ability of entrapped hepatocytes to secrete plasma proteins was examined for the purpose of developing a biological artificial liver. Hepatocytes were isolated from adult rat liver by perfusion with collagenase. Isolated hepatocytes were entrapped within calcium alginate. The entrapped cells induced tyrosine aminotransferase (TAT) in the presence of dexamethasone and dibutyryl-cyclic AMP and retained the ability to induce TAT for 7 days. Moreover, entrapped cells could synthesize and secrete a biologically active form of coagulation Factor II, prothrombin. Two plasma proteins, lecithin: cholesterol acyltransferase and cholinesterase, were also secreted into the medium. Thus, hepatocytes within calcium alginate showed liver-specific characteristics, and these activities were almost comparable with those of monolayer-cultured cells.
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PMID:Synthesis and secretion of protein by hepatocytes entrapped within calcium alginate. 287 25

Two different preparations of the rat phrenic nerve-hemidiaphragm (whole nerve-muscle preparation, end-plate preparation) were used for studying synthesis and release of radioactive acetylcholine in the absence and presence of cholinesterase inhibitors. When the whole nerve-muscle preparation (110-180 mg) was incubated with [3H]choline, only small amounts of radioactive acetylcholine were synthesized within the tissue. Electrical nerve stimulation of the whole nerve-muscle preparation produced no increase in tritium outflow. Incubation of the end-plate preparation (16-29 mg) which was obtained after removal of most of the muscle mass led to the formation of large amounts of [3H]acetylcholine. Synthesis depended on nerve activity and increased 13-fold during a high loading stimulation (50 Hz), as compared to the synthesis at rest. In a denervated end-plate preparation the formation of [3H]acetylcholine was reduced to 4% of the control preparation. Electrical nerve stimulation of the end-plate preparation produced a release of tritium that could be attributed entirely to the release of [3H]acetylcholine. The stimulated tritium efflux was completely suppressed in a calcium-free medium or in the presence of tetrodotoxin (300 nM). Release could even be detected during a short train of 50 pulses (5 Hz) with a fractional release of about 0.04% of the [3H]acetylcholine tissue content per pulse. It is concluded that the large muscle mass interferes with nerve labelling by a reduction of the [3H]choline supply to the nerve terminals when the whole nerve-muscle preparation is used.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Release of [3H]acetylcholine from a modified rat phrenic nerve-hemidiaphragm preparation. 288 Dec 15

The number of quanta secreted from selected sites along terminal branches at toad (Bufo marinus) neuromuscular junctions was determined. Terminal branches were visualized by prior staining with the fluorescent dye, 3-3 Diethyloxadicarbocyanine iodide (DiOC2(5)); neither impulse conduction nor quantal release were affected by DiOC2(5) at concentrations less than 10 microM. The evoked quantal release recorded with an extracellular micro-electrode (me) at different sites along the length of terminal branches was determined in an external calcium concentration, [Ca]o, of 0.35-0.45 mM. For short branches (40-80 microns), me remained approximately constant for over 60% of the branches; for the rest, me declined approximately exponentially with an average length constant of 17 +/- 2 microns (mean +/- S.E. of mean). For both medium (81-120 microns) and long branches (121-160 microns), me declined in nearly all cases approximately exponentially with length constants of 39 +/- 5 and 54 +/- 8 microns respectively. These changes in me were observed at synapses having a wide range of terminal branching patterns. Some DiOC2(5)-stained branches possessed discontinuous cholinesterase staining. In general, me declined along these branches in the same way as along DiOC2(5)-stained branches with continuous cholinesterase staining. It is suggested that because of the decline in me along most medium and long terminal branches, many release sites have a very low probability for secretion in low [Ca]o. Release sites near the point of nerve entry, which have a relatively high probability, therefore make the main contribution to secretion recorded with an intracellular micro-electrode. As a consequence, transmitter secretion from the whole terminal does not fluctuate from impulse to impulse as much as expected if there were a large number of release sites, each with a low probability of secretion. Transmitter secretion then follows binomial rather than Poisson statistics.
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PMID:The probability of quantal secretion along visualized terminal branches at amphibian (Bufo marinus) neuromuscular synapses. 288 19

Acetylcholinesterase (AchE: EC 3.1.1.7) was identified and purified from the hemolymph of the scorpion Heterometrus bengalensis. The purity of the enzyme was determined by polyacrylamide gel electrophoresis (PAGE). The molecular weight of the enzyme, determined by sodium dodecyl sulfate-PAGE, was 80,000. The purified AchE hydrolysed acetylthiocholine iodide, but it did not react with butyrylthiocholine iodide. BW284C51, a specific inhibitor of AchE, strongly inhibited the enzyme. The known inhibitor (tetramonoisopropylpyrophosphortetramide) of pseudocholinesterase did not produce any inhibition of the enzyme activity. The purified AchE of scorpion hemolymph was vulnerable to high substrate concentration. The presence of Cu2+ and Ni2+ reduced the enzyme activity, whereas the metal ion, Sn2+, enhanced AchE activity. Ca2+ produced neither inhibition nor activation. (Na+, K+)-ATPase and Mg2+-ATPase activities were greatly enhanced by the purified AchE.
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PMID:Acetylcholinesterase (EC 3.1.1.7), a neurotransmitter enzyme in scorpion hemolymph. 296 37

Synaptic transmission in the bullfrog sympathetic ganglion was studied by means of extra- and intracellular recordings. DMSO (3-10%) caused a single orthodromic stimulus to generate a brief burst of repetitive postganglionic discharges. DMSO also partially reversed a preexisting transmission failure in low Ca2+ medium. Ganglia were exposed to gradual reductions in extracellular Ca2+, in the absence and in the presence of DMSO. The recorded amplitude of the postganglionic compound action potential (CAP) was plotted as a function of Ca2+ concentration. In the absence of DMSO transmission failed progressively as Ca2+ was reduced from 1.8 to 0.47 mM but DMSO (3% and 10%) shifted the curve of transmission failure to the left (lower Ca2+ concentration). DMSO inhibits ganglion cholinesterase activity, but this is not the mechanism of its facilitatory effect on Ca2+ entry, since physostigmine did not shift the curve of transmission failure in low Ca2+ to the left. The data suggest that DMSO maintained transmitter release in low Ca2+ by a direct, nonspecific enhancement of Ca2+ influx into the presynaptic nerve terminal.
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PMID:DMSO effects on synaptic facilitation and calcium dependence in bullfrog sympathetic ganglion. 298 96

These experiments measured the release and the synthesis of acetylcholine (ACh) by cat sympathetic ganglia in the presence of 2-(4-phenylpiperidino) cyclohexanol (AH5183), an agent that blocks the uptake of ACh into synaptic vesicles. Evoked transmitter release during short periods of preganglionic nerve stimulation was not affected by AH5183, but release during prolonged stimulation was not maintained in the drug's presence, whereas it was in the drug's absence. The amount of ACh releasable by nerve impulses in the presence of AH5183 was 194 +/- 10 pmol, which represented 14 +/- 1% of the tissue ACh store. The effect of AH5183 on ACh release was not well antagonized by 4-aminopyridine (4-AP), and not associated with inhibition of stimulation-induced calcium accumulation by nerve terminals. It is concluded that AH5183 blocks ACh release indirectly, and that the proportion of stored ACh releasable in the compound's presence represents transmitter in synaptic vesicles available to the release mechanism. The synthesis of ACh during 30 min preganglionic stimulation in the presence of AH5183 was 2,448 +/- 51 pmol and in its absence it was 2,547 +/- 273 pmol. Thus, as the drug decreased ACh release it increased tissue content. The increase in tissue content of ACh in the presence of AH5183 was not evident in resting ganglia; it was evident in stimulated ganglia whether or not tissue cholinesterase was inhibited; it was increased by 4-AP and reduced by divalent cation changes expected to decrease calcium influx during nerve terminal depolarization.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Acetylcholine synthesis and release by a sympathetic ganglion in the presence of 2-(4-phenylpiperidino) cyclohexanol (AH5183). 300 95

The interaction of spin-labeled metacyn, procaine, carbolin and bivalent cations (Ca2+, Co2+, Ni2+) with butyrylcholinesterase (BChE) was studied by ESR and enzyme kinetic methods. The effect of pH, ionic strength and organic solvent was analysed. Spin-labeled metacyn binds at the anionic site of BChE active centre. This complex is stabilized both with coulombic and hydrophobic interactions, ionizing group of active centre with pK 6-7 also affects the binding. Spin-labeled procaine appeared to be enzyme competitive inhibitor (Ki = 4 X 10(-5) M) and is located, most probably, at the same site. Activating effect of Ca2+ ions on BChE was confirmed. Simultaneous application of spin labels and paramagnetic ions demonstrates that cations Co2+ and Ni2+ bind with BChE in the close vicinity of spin-labeled inhibitor site. Paramagnetic cations are located more closely to the cationic part of the inhibitor molecule than to the hydrophobic one, and can be displaced by surplus of Ca2+ ions. The experimental data testify the model of anionic centre which consists of bivalent metal ions and aminoalcyl cationic group subsites and is located in a hydrophobic pocket of the enzyme surface.
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PMID:[Binding of reversible spin-labeled inhibitors with an butyrylcholinesterase active center]. 302 29

Depolarisation of [3H]inositol prelabelled slices of cerebral cortex of the rat, with elevated extracellular K+ or the alkaloid veratrine, induced a marked accumulation of [3H]inositol monophosphate in the presence of 5 mM Li+. The effects of these stimuli were concentration-related with maximal responses obtained at 30 mM K+ and 30 microM veratrine. Larger concentrations produced submaximal responses but also markedly suppressed the incorporation of [3H]inositol into phospholipid. The responses to K+ or veratrine were not sensitive to atropine, prazosin, mepyramine, ketanserin or the peptidase inhibitor bacitracin. However, in the presence of the cholinesterase inhibitor physostigmine, the responses to these stimuli were greatly enhanced and this could be blocked by atropine. Both veratrine and K+ markedly stimulate release of endogenous acetylcholine from the slices. Release appears to be linear with time over the 45 min period of continuous stimulation. Reduction of extracellular calcium severely suppressed both the release of acetylcholine and the atropine-sensitive component of the phosphoinositide response to K+. The results suggest that endogenous acetylcholine can stimulate phosphoinositide metabolism by interacting with muscarinic receptors. The atropine-insensitive component, at least in part, represents entry of Ca2+ through voltage-sensitive channels and perhaps a direct effect on phosphoinositide metabolism.
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PMID:Depolarisation-evoked release of acetylcholine can mediate phosphoinositide hydrolysis in slices of rat cerebral cortex. 303 20

It is demonstrated by experiments with rabbits that the Ca2+-ATP-ase activity is stabilized when using combined anesthetics (diacetylcholine + halothane + N2O) as distinct from application of halothane. A decrease in the cholinesterase activity is less pronounced than under the halothane action but more than with the diacetylcholine application. A decrease in the Na+, K+-ATP-ase activity is observed with all types of anesthesia. A considerable inhibition of creatine kinase under the action of combined anesthesia and halothane and an increase of the lactate dehydrogenase activity under diacetylcholine application in mitochondria are shown. Reliable differences in the succinic dehydrogenase activity are not detected.
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PMID:[Effect of combined anesthetics on the activity of various myocardium enzymes]. 303 46

1. Using a K+-sensitive extracellular electrode, we attempted to determine whether cholinergic stimulation of the simian palm eccrine sweat gland is associated with transient net K+ efflux as in other exocrine glands. 2. When isolated secretory coils placed in a glass capillary were continuously superfused (method A), 32% of total cellular K+ was lost during 3 min of stimulation with methacholine (MCh) followed by K+ reuptake when stimulation was stopped. 3. When secretory coils were stimulated in a small chamber (without continuous superfusion, method C), MCh (5 x 10(-6) M)-induced maximal K+ efflux as determined by the peak level of extracellular K+ concentrations was dose dependent, inhibited by atropine but not altered by a cholinesterase inhibitor, physostigmine (1.3 x 10(-5) M). Thus the peak K+ level was used as a measure of K+ efflux throughout the study. 4. Phenylephrine (10(-4) M) and A23187 (5 x 10(-6) M) also induced K+ efflux but to a lesser extent than did MCh. 5. Ouabain (10(-3) M)-induced K+ loss was 2.4-fold higher than the peak level of MCh-induced K+ efflux. 6. In a Ca2+-free medium with added EGTA, inhibition of K+ efflux was only partial in the first MCh stimulation but progressively increased on repeated stimulation, suggesting that cytoplasmic or membrane Ca2+ not readily accessible to EGTA may be important for K+ efflux. Inhibition of K+ efflux in the Ca2+-free medium was completely reversed on subsequent addition of Ca2+. 7. Five millimolar Ba2+ partially inhibited MCh-induced K+ efflux. 8. 10(-4) M-bumetanide itself caused a small K+ loss and strongly inhibited the subsequent MCh-induced K+ loss. 9. MCh-induced K+ loss was drastically inhibited in the low-Cl- (by replacing with gluconate- or methylsulphate-) or low-Na+ (by replacing with Tris+) medium. 10. K+ efflux occurs predominantly across the basolateral membrane. 11. Vinblastine at 10(-4) M, which completely inhibits sweat secretion (our unpublished results), however, showed no effect on MCh-induced K+ efflux. 12. We conclude that the transient net K+ efflux associated with MCh stimulation constitutes a crucial primary ionic event in cholinergic eccrine sweat secretion as in other exocrine secretory cells.
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PMID:K+ efflux from the monkey eccrine secretory coil during the transient of stimulation with agonists. 315 70


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