A transient calcium‐dependent chloride current in the immature Xenopus oocyte.

Barish, Michael E.

doi:10.1113/jphysiol.1983.sp014852

Cited by 600 publications

(424 citation statements)

References 49 publications

(62 reference statements)

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“…Comparable degrees of inhibition were observed at positive and negative holding potentials suggesting no voltage dependence (Figure 2a). The reversal potentials were not significantly different from one another (À24.473.5 (GABA) and À22.073.6 mV (GA-BA þ SCS)), and are close to the predicted reversal potential for Cl À ions of À25.4 mV in Xenopus oocytes, with an external Cl À concentration of 89.91 mM (MBS used in this study) and an internal Cl À concentration of 33.4 mM (Barish, 1983 (Figure 2b). …”

Section: Inhibition By Scs Is Not Voltage or Use Dependentsupporting

confidence: 80%

Salicylidene salicylhydrazide, a selective inhibitor ofβ1‐containing GABA_Areceptors

Thompson

Wheat

Brown

et al. 2004

British J Pharmacology

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1 A high-throughput assay utilizing the voltage/ion probe reader (VIPR) technology identified salicylidene salicylhydrazide (SCS) as being a potent selective inhibitor of a2b1g1y GABA A receptors with a maximum inhibition of 5675% and an IC 50 of 32 (23, 45) nM. 2 Evaluation of this compound using patch-clamp electrophysiological techniques demonstrated that the compound behaved in a manner selective for receptors containing the b1 subunit (e.g. maximum inhibition of 68.172.7% and IC 50 value of 5.3 (4.4, 6.5) nM on a2b1g1 receptors). The presence of a b1 subunit was paramount for the inhibition with changes between a1 and a2, g1 and g2, and the presence of a y subunit having little effect. 3 On all subtypes, SCS produced incomplete inhibition with the greatest level of inhibition at a1b1g1y receptors (74.371.4%). SCS displayed no use or voltage dependence, suggesting that it does not bind within the channel region. Concentration -response curves to GABA in the presence of SCS revealed a reduction in the maximum response with no change in the EC 50 or Hill coefficient. In addition, SCS inhibited pentobarbitone-induced currents. 4 Threonine 255, located within transmembrane domain (TM) 1, and isoleucine 308, located extracellularly just prior to TM3, were required for inhibition by SCS. 5 SCS did not compete with the known allosteric modulators, picrotoxin, pregnenolone sulphate, dehydroepiandrosterone 3-sulphate, bicuculline, loreclezole or mefenamic acid. Neither was the inhibition by SCS influenced by the benzodiazepine site antagonist flumazenil. 6 In conclusion, SCS is unique in selectively inhibiting GABA A receptors containing the b1 subunit via an allosteric mechanism. The importance of threonine 255 and isoleucine 308 within the b1 subunit and the lack of interaction with a range of GABA A receptor modulators suggests that SCS is interacting at a previously unidentified site.

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Section: Inhibition By Scs Is Not Voltage or Use Dependentsupporting

confidence: 80%

Salicylidene salicylhydrazide, a selective inhibitor ofβ1‐containing GABA_Areceptors

Thompson

Wheat

Brown

et al. 2004

British J Pharmacology

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“…Half-maximally effective concentrations of NKB and NKA were 4 nM and 40 nM, respectively. A reversal potential of -30 mV, close to the equilibrium potential for chloride, indicates that a Ca~%sensitive chloride channel is activatext [27].…”

Section: Resultsmentioning

confidence: 93%

Molecular characterisation, expression and localisation of human neurokinin‐3 receptor

Buell¹,

Schulz²,

Arkinstall³

et al. 1992

FEBS Letters

101

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The complete amino acid sequence of the human neurokinin-3 receptor was deduced by DNA sgqumtco analysis of human genomic fragments. Comparison of the predicted primary structure with those for the human neurokinin receptors 1 and 2 shows a highly conserved pattern of seven hydrophobi¢ regions with maximum divergence oceuring at the amino-and carboxy-terrnini, The position of intron-exon junctions are identical to those in other reported neurokinin genes, Using a chimeric genomic.cDNA gone, the human NK-3 receptor was expressed in Xenopus laevts oooytes where it mediates membrane conductance changes in response to its agonist, neurokinin B. More significantly, expression of the 8ene in mammalian cells resulted in detection of receptor binding as well as neurokinin-stimulated calcium mobilization and araehidonie acid release, all displaying the pharmacological characteristics expected of a nearokinin-3 receptor, By using the polymerase chain reaction we have shown that mRNA for the human neurokinin-3 receptor is expressed predominantly in the egntral nervous system,

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“…2A, 3), which corresponds to the chloride equilibrium potential in Xenopus oocytes (Barish, 1983;Kusano et al, 1982). This reversal potential is similar to that of GABAactivated channels induced in the oocyte by chick optic lobe mRNA and also to the chloride channels activated by ACh (muscarinic receptors), SHT, and glycine (Gundersen et al, 1983a(Gundersen et al, , 1984aKusano et al, 1982).…”

Section: Resultsmentioning

confidence: 99%

Actions of pentobarbital on rat brain receptors expressed in Xenopus oocytes

Parker¹,

Gundersen²,

Miledi³

1986

J. Neurosci.

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Functional receptor channels activated by GABA and other neurotransmitters were “transplanted” from rat brain to Xenopus oocytes by injecting the oocytes with total poly(A)+ mRNA isolated from rat or chick brain. Membrane currents elicited in the oocyte by GABA inverted polarity at about the chloride equilibrium potential (ca. -25 mV). Pentobarbital potentiated the GABA-activated currents, without appreciably changing the reversal potential or form of the current- voltage relationship. At low (less than 10(-5) M) concentrations of GABA, pentobarbital (100 microM) potentiated the responses by a factor of 10 or more, but responses to high (ca. 1 mM) concentrations of GABA were almost unchanged. Half-maximal activation of the response was obtained with about 3 X 10(-5) M GABA when applied alone and with about 4 X 10(-6) M GABA when applied together with 100 microM pentobarbital. At low doses of GABA, the size of the current increased as the 1.4th power of GABA concentration, but this relationship became nearly linear in the presence of pentobarbital. The potentiation of the GABA response increased linearly with concentrations of pentobarbital up to about 300 microM, reaching a maximum of about 50-fold. At higher concentrations of pentobarbital, the response to GABA declined. Relaxations of GABA- activated currents following voltage steps became slower in the presence of pentobarbital, suggesting that the open life-time of the channels was prolonged. In addition to actions on GABA-activated currents, pentobarbital itself elicited a small membrane current that inverted polarity at a potential (-10 mV) more positive than the GABA- activated current.(ABSTRACT TRUNCATED AT 250 WORDS)

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A transient calcium‐dependent chloride current in the immature Xenopus oocyte.

Cited by 600 publications

References 49 publications

Salicylidene salicylhydrazide, a selective inhibitor ofβ1‐containing GABA_Areceptors

Salicylidene salicylhydrazide, a selective inhibitor ofβ1‐containing GABA_Areceptors

Molecular characterisation, expression and localisation of human neurokinin‐3 receptor

Actions of pentobarbital on rat brain receptors expressed in Xenopus oocytes

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A transient calcium‐dependent chloride current in the immature Xenopus oocyte.

Cited by 600 publications

References 49 publications

Salicylidene salicylhydrazide, a selective inhibitor ofβ1‐containing GABAAreceptors

Salicylidene salicylhydrazide, a selective inhibitor ofβ1‐containing GABAAreceptors

Molecular characterisation, expression and localisation of human neurokinin‐3 receptor

Actions of pentobarbital on rat brain receptors expressed in Xenopus oocytes

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Product

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Salicylidene salicylhydrazide, a selective inhibitor ofβ1‐containing GABA_Areceptors

Salicylidene salicylhydrazide, a selective inhibitor ofβ1‐containing GABA_Areceptors