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:3.4.16.2 (PCP)
3,761 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

[3H]Phencyclidine (PCP) binds to a single class of noninteracting binding sites in rat brain membranes with an affinity Kd of 0.25 microM and a maximal binding capacity BM of 2.4 pmol/mg of membrane protein. PCP derivatives also interact with the muscarinic and mu-opiate receptors in rat brain membranes with affinities that are one or two orders of magnitude lower than those observed for the [3H]PCP-binding sites. Activities of 25 PCP derivatives in the rotarod assay are closely correlated to affinities of these molecules for the [3H]PCP-binding sites, but not for the muscarinic or mu-opiate receptors. Monohydroxylation of PCP generally decreases the affinity of PCP for the [3H]PCP- and muscarinic-binding sites and does not change the affinity for the mu-opiate receptor. The metaphenolic derivative of PCP does not follow these general rules; the affinities of this derivative for the [3H]PCP- and mu-opiate-binding sites are 8 and 430 times higher, respectively, than those of PCP itself. Voltage-clamp experiments with N1E 115 neuroblastoma cells show that PCP is an efficient blocker of both the K+ channel (EC50 = 2.6 microM) and the Na+ channel (EC50 = 9.2 microM).
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PMID:Identification and properties of phencyclidine-binding sites in nervous tissues. 630 60

Phencyclidine (1-(1-phenylcyclohexyl)piperidine [PCP]), a behaviorally active analogue (1-(1-m-aminophenylcyclohexyl)piperidine [m-amino-PCP]), and two behaviorally inactive analogues (1-(1-m-nitrophenylcyclohexyl)piperidine and 1-piperidinocyclohexanecarbonitrile) block neuromuscular transmission, depress the amplitude and rate of rise of directly elicited action potentials in frog sartorius muscle, and cause voltage- and concentration-dependent decreases of the peak end-plate current amplitude. This implies that all four compounds block the ion channel of the acetylcholine (ACh) receptors. Only PCP and m-amino-PCP prolong the action potential, block delayed rectification, potentiate muscle twitch, increase quantal content of end-plate potentials, and block K+-induced 86Rb+ efflux from rat brain synaptosomes. PCP also possesses central and peripheral antimuscarinic activity but is much less potent than 3-quinuclidinyl benzilate (QNB). Atropine, scopolamine, and QNB require much higher concentrations to induce behavioral alterations than to block muscarinic receptors. Thus PCP and some of its behaviorally active and inactive derivatives share two common effects, blockade of the nicotinic ACh receptor-ion channel complex and blockade of central and peripheral muscarinic receptors. The feature that apparently separates behaviorally active from inactive derivatives of PCP is their ability to block K+ conductance (gK) and thereby potentiate muscle twitch and increase the release of transmitters from central and peripheral synapses. The similarity between PCP-induced behavioral alterations and primary schizophrenia in humans raises the possibility of involvement of an altered gK in the human disease.
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PMID:Interactions of phencyclidine with ion channels of nerve and muscle: behavioral implications. 630 62

Phencyclidine [1-(phenylcyclohexyl)piperidine; PCP], in low dose (approximately equal to 0.1-0.2 mg/kg of body weight), induces a schizophrenia-like behavioral syndrome in man; this effect has been attributed to block of neuronal K channels. We used a K-stimulated 86Rb efflux assay to demonstrate that low concentrations of PCP (10-50 nM) block a class of depolarization-activated K channels in rat brain synaptosomes--pinched-off presynaptic nerve terminals. The dose-response curve is biphasic, and much higher PCP concentrations (greater than 10 microM) are required to block the remainder of the K-stimulated 86Rb efflux. The [3H]PCP binding curve for synaptosomes is also biphasic: PCP binds to some components with high affinity (Kd approximately equal to 6.0 X 10(-8) M), and to other components with much lower affinity (Kd approximately equal to 1.15 X 10(4) M). PCP can be photoactivated with UV light to form covalent bonds: after UV irradiation, previously-bound [3H]PCP is no longer displaceable by a large excess of unlabeled PCP. Preliminary data from NaDodSO4/polyacrylamide gel electrophoresis studies after covalent binding of [3H]PCP to synaptosomes, suggest that the high-affinity binding site may be on a large protein (Mr approximately equal to 220,000). We conclude that the high-affinity PCP binding protein is associated with the K channels that are blocked by nanomolar concentrations of PCP. Block of these channels could, by prolonging action-potential duration in presynaptic nerve terminals, enhance calcium entry and neurotransmitter release, thereby altering transmission at central synapses involved in behavioral expression.
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PMID:Phencyclidine in nanomolar concentrations binds to synaptosomes and blocks certain potassium channels. 630 43

(3H)-Phencyclidine (PCP) binds specifically to the cholinergic ionophore in synaptic membranes prepared from Torpedo electric organ. Experiments performed by the centrifugation method establish that the binding is saturable, reversible and selective and can be characterized by a single dissociation constant (3.6 +/- 1.8 microM). The maximal binding capacity is 600 +/- 150 pmol/mg of membrane protein. Bound (3H)-PCP can be displaced by unlabelled PCP and a series of its derivatives. The reactivity of PCP derivatives in binding to (3H)-PCP binding sites, as related to structural changes at the phenyl, piperidyl and cyclohexyl moieties, is discussed.
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PMID:Characterization of the interaction of phencyclidine and its derivatives with the ionic channel of the nicotinic receptor. 631 26

[3H]Phencyclidine (PCP, Angel Dust) receptors have been characterized using a rat brain binding section technique. [3H]PCP labels a single class of site in rat brain (KD = 46 nM; Bmax = 10.5 fmol/slice). Ligand selectivity pattern strongly suggests that [3H]PCP binds to sites relevant for its pharmacological actions. Chronic PCP treatment (10 mg/kg/day for 14 days) decreases the number of sites (Bmax) for [3H]PCP and [3H]spiperone binding but not for [3H]dihydromorphine. These modifications could be related to the development of tolerance and dependence to PCP. Visualization of [3H]PCP binding sites shows high densities of receptors in cortical areas and hippocampus. Lower densities are observed in caudate-putamen, nucleus accumbens, and amygdala. Negligible quantities of receptors are seen in brain stem and over white matter. The presence of specific [3H]PCP binding sites in rat brain suggests the possible existence of an endogenous ligand for this unique receptor.
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PMID:Properties of the phencyclidine (PCP) receptors. 632 Feb 96

[3H]Phencyclidine ([3H]PCP) binding was studied in guinea-pig ileum muscle membranes. Specific binding of [3H]PCP was time dependent, reversible and saturable, with an equilibrium dissociation constant of 154 nM and maximum binding of 12.9 pmol/mg of protein at pH 9. Its pH dependency suggests that the unionized PCP is the pharmacologically active form. The binding site was on a protein which was sensitive to heat, proteolytic enzymes and the carboxylic group reagent dicyclohexylcarbodiimide, but insensitive to phospholipase A and C, concanavalin A, dithiothreitol and N-ethylmaleimide. Specific [3H]PCP binding was displaced effectively by several PCP analogs and Ca++ channel antagonists including verapamil, to which these sites had a high affinity. These high-affinity PCP-binding sites were found at a much higher concentration in the same membrane preparation than muscarinic receptor sites identified by their specific binding of [3H]quinuclidinyl benzilate. PCP bound to both sites, but with a lower affinity to the muscarinic receptor sites. The PCP and muscarinic receptor sites differed in their sensitivities to pH and drug specifities .
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PMID:Distinction between high-affinity [3H]phencyclidine binding sites and muscarinic receptors in guinea-pig ileum muscle. 632 65

[3H]Phencyclidine ( [3H]PCP) bound to crayfish abdominal muscle membranes at pH 7.4 with two affinities (Kd of 0.96 nM for 0.38 pmole/mg of protein, and 18.9 nM for 7.6 pmoles/mg of protein). Binding affinities increased at higher pH, suggesting that binding may be due mostly to the un-ionized form of [3H]PCP. This high-affinity [3H]PCP binding was sensitive to the actions of trypsin, protease, and dicyclohexylcarbodiimide, but insensitive to phospholipase A, concanavalin A,N-ethylmaleimide, and dithiothreitol. Calcium channel antagonists were most potent in inhibiting the high-affinity [3H]PCP binding with the following descending order of potencies: bepridil greater than nicardipine = diltiazem = verapamil greater than cinnarizine greater than (+)-D-600 greater than (-)-D-600 greater than 4-NO2-nifedipine greater than 2-NO2-nifedipine. The binding was also highly sensitive to several PCP analogues, antipsychotics, piperocaine , and tilorone, and moderately sensitive to d-tubocurarine, atropine, imipramine, nortryptyline , and tetracaine. Although verapamil and nifedipine inhibited the action potential of crayfish muscle, PCP did not and actually prolonged slightly the falling phase of the action potential. Although it is unlikely that the [3H]PCP binding protein in crayfish muscles is a Ca2+ channel, it is possible that it may be a K+ channel.
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PMID:Interactions of phencyclidine with crayfish muscle membranes. Sensitivity to calcium channel antagonists and other drugs. 632 63

Phencyclidine ("PCP" or "angel dust") and some of its derivatives are psychotomimetic drugs that have been used in general anesthesia for some time. This drug blocks potassium ion channels in brain tissue, and there is a specific PCP binding to lymphocytes. In a study of the effects of this drug on immunocyte function, it was found that humoral and cellular immune responses in vitro were depressed when immunocytes were treated with PCP before biological assay. This finding has implications for PCP abuse and also for the use of its derivative in general anesthesia, where it may contribute to postoperative infection.
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PMID:Phencyclidine-induced immunodepression. 632 64

Phencyclidine (PCP) in serum (5 ng/mL and higher) was quantitated by a homogeneous enzyme immunoassay procedure. Precision and accuracy data indicate that the procedure meets the requirements for a clinical assay. The short turnaround time for the assay makes it superior to other available methods for the emergency determination of PCP in serum. The analytical results were comparable to those by GC/MS on 70 samples tested. The serum concentration of PCP was determined in 500 specimens from 405 patients. In 216 patients with "pure" PCP intoxication, the serum concentration did not show a direct relationship to either the clinical pattern of intoxication or to the history of the route of PCP use.
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PMID:Quantitation of phencyclidine in serum by enzyme immunoassay: results in 405 patients. 634 23

Phencyclidine (PCP) is a major drug of abuse as well as a 'drug of choice' among substance abusers in the U. S. A. Unfortunately, PCP use may result in the development of psychotic behavior. PCP-induced psychosis is characterized by confusion, excitation, aggression, paranoia, hallucinations and delusions of grandeur and may evoke violent or suicidal behavior. Therefore, many patients suffering from PCP-induced psychosis have been diagnosed initially as schizophrenic. However, PCP-related research has not kept pace with the rise in abuse and PCP-induced psychosis. The neurochemical effects of PCP are not well defined at present, but both behavioral and biochemical studies suggest that it may interact with dopaminergic, cholinergic, noradrenergic, serotonergic, GABAergic and enkephalinergic systems. In addition, the specific reversible, saturable, high affinity 3H-PCP binding site is discovered recently in rat brain. On the other hand, there is now a large body of evidence to suggest that opiate receptors may be subdivided into mu, sigma, kappa and delta receptors. On the basis of behavioral and binding studies, it is proposed that the sigma receptor and the PCP binding site are one and the same. This receptor interacts with PCP and psychotomimetic opioids to produce their psychotomimetic effects. In connection with this receptor, a trial to isolate an endogenous ligand produces psychotomimetic effects, "angeldustin" is progressing. This review has served to illustrate the paucity of information currently available on the central effects of PCP. However, our current notions of the mechanisms of action of PCP are very complicate. Such a review inevitably raises more question than it answers but it is hoped that these may stimulate further investigation in this field.
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PMID:[Phencyclidine, a drug which induces psychosis: its neuropharmacological actions]. 639 56


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