Direct and indirect effects of sulfhydryl blocking agents on agonist and antagonist binding to central α1- and α2-adrenoceptors

Quennedey, M. C.; Bockaert, Joël; Rouot, Bruno

doi:10.1016/0006-2952(84)90002-9

Cited by 22 publications

(4 citation statements)

References 18 publications

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“…Recently, low concentrations of pCMBS and pCMB have been found to activate specific membrane receptor processes in a range of tissues and interestingly, the activated process can itself be regulated by natural agonists and antagonists (Quennedy et al 1984). These very specific effects of complexing membrane SH groups are similar to the activation of specific conductance pathways which we find occur at low concentrations of pCMPS (Fig.…”

Section: Discussionsupporting

confidence: 68%

“…Recent work, where much lower concentrations of membrane SH-blocking agents have been used, has in fact revealed quite specific membrane processes that are controlled by SH groups. For example, Quennedy, Bockaert & Rouott (1984) have found that micromolar concentration of pCMBS will reduce agonist and antagonist binding in aland ac2-adrenoreceptors, and it is interesting that the blockade can be reversed by natural agonists and antagonists. Low concentrations of pCMB (pchloro-mercuribenzene) also inhibit the response of several tissues to adrenaline and noradrenaline and the inhibition is reversed by SH-containing molecules (Tongia & Pandya, 1984).…”

Section: Introductionmentioning

confidence: 99%

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p‐chloro‐mercuriphenyl sulphonate activates a quinine‐sensitive potassium conductance in frog lens.

Duncan

Emptage

Hightower

1988

The Journal of Physiology

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SUMMARY1. The effects of the sulphydryl-complexing reagent p-chloro-mercuriphenyl sulphonate (pCMPS) on membrane voltage and electrical conductance were studied on the isolated frog lens.2. At low concentrations (01-50 ,sM) pCMPS induced a rapid and graded hyperpolarization of the lens membrane potential which saturated at -97 mV.3. The lens conductance also showed a graded increase, but the initial changes were apparent only at concentrations above 1 /tM.4. Decreasing the external potassium concentration from 2-5 to 0-5 mm had little effect on the membrane potential in the absence of pCMPS, but increased the voltage from -97 to -110 mV when pCMPS was present.5. Quinine (300 /,lM) had no effect when added in control solution, but depolarized the membrane potential and decreased the conductance when added to a pCMPStreated preparation.6. These data suggest that pCMPS activates voltage-sensitive potassium channels that are quiescent at the frog resting potential in control solution.7. At pCMPS concentrations > 100 /,M, the initial hyperpolarization is followed by a marked but slow depolarization of the membrane potential and a further increase in lens conductance. These data suggest that non-specific cation channels are activated in this case.8. Cysteine (5 mM) added to a pCMPS-treated lens leads to a rapid recovery of membrane potential and conductance to near their resting values whether the lens had previously been exposed to low or high concentrations of pCMPS.9. All of these changes in lens voltage and conductance occurred without apparent alteration in the lens internal sulphydryl content.

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Section: Discussionsupporting

confidence: 68%

Section: Introductionmentioning

confidence: 99%

p‐chloro‐mercuriphenyl sulphonate activates a quinine‐sensitive potassium conductance in frog lens.

Duncan

Emptage

Hightower

1988

The Journal of Physiology

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“…The manganese-induced ternary A -R * G complex was converted into the binary A -R complex by additional NEM. In recent communications, it has been shown that pretreatment with NEM does not change the binding of a2-antagonists but that NEM produces binding changes similar to those induced by GTP in control membranes in competition experiments using [3H]rauwolscine versus unlabeled norepinephrine (Jakobs et al, 1982;Quennedey et al, 1984). It seems that NEM affects the binding of agonist specifically.…”

Section: Discussionmentioning

confidence: 99%

Uncoupling of Rat Cerebral Cortical α₂‐Adrenoceptors from GTP‐Binding Proteins by N‐Ethylmaleimide

Kitamura

Nomura

1987

Journal of Neurochemistry

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Pretreatment of membranes from rat cerebral cortex with N-ethylmaleimide (NEM) decreased [3H]-clonidine binding in a concentration-dependent manner. The Bmax values of high-affinity sites for [3H]clonidine were reduced by 50 microM NEM treatment. Treatment with 500 microM NEM diminished the sum of Bmax of both high- and low-affinity components. GTP, Na+, and Mn2+ exerted little effect on [3H]clonidine binding in NEM-treated membranes. The addition of purified GTP-binding proteins caused an increase in the binding to the membranes pretreated with 50 microM NEM, but did not increase [3H]-clonidine binding in membranes treated with 500 microM NEM. In contrast, NEM pretreatment inhibited islet activating protein (IAP)-catalyzed ADP ribosylation of membrane-bound (41,000-dalton) and purified (39,000/41,000-dalton) GTP-binding proteins. From these results, it is suggested that two or three categories of essential sulfhydryl groups are involved in the coupling between agonist, alpha 2-adrenoceptor, and GTP-binding protein. One is a highly sensitive site to NEM (a concentration range of 1-50 microM), which is probably a cysteine residue, IAP-catalyzed ADP-ribosylating site on the alpha-subunit of GTP-binding protein. Other sites have low sensitivity to NEM (a concentration range of 0.1-1 mM), and are the binding domain of agonist and/or the coupling domain of GTP-binding protein on the alpha 2-adrenoceptor. In addition, Ki-ras p21 protein may lack the capacity to couple with the alpha 2-adrenoceptor.

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“…Because receptors are protein in nature, the use of re-Abbreviations used: CPU, neostriatum or caudate-putamen; CTX, cerebral cortex; DA, dopamine; DTE, dithioerythritol; DTNB, 5,5'dithiobis(2-nitrobenzoic acid); DTT, dithiothreitol; NEM, N-ethylmaleimide. agents which modify these groups may influence the interaction of neurotransmitters with their recognition sites. Thus, -SSand -SH reactives have proven useful in the characterization of cholinergic nicotinic (Karlin and Bartels, 1966;Del Castillo et al, 1971;Sobrino and Del Castillo, 1972;Barrantes, 1980), cholinergic muscarinic (Aronstam et al, 1978;Ehlert et al, 1980), /I-adrenergic (Lucas et al, 1978;Stadel and Lefkowitz, 1979), a-adrenergic (Quennedy et al, 1984;Reader and Bri;re, 1985;Lakhdar-Ghazal et al, 1986;Reader et al, 1986), and opiate (Nozaki and Cho, 1985) receptors. These reagents also have been utilized to investigate the properties of DA receptor sites.…”

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confidence: 99%

Specific [³H]SCH23390 Binding to Dopamine D₁ Receptors in Cerebral Cortex and Neostriatum: Role of Disulfide and Sulfhydryl Groups

Dewar

Reader

1989

Journal of Neurochemistry

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Receptor binding studies were performed in cerebral cortex (CTX) and neostriatum (CPU; caudate-putamen) using the dopamine D1 antagonist [3H]SCH23390. Because receptors are of protein nature, we examined the role of disulfide bonds (--SS--) and sulfhydryl groups (--SH) in the specific binding of [3H]SCH23390. Furthermore, membrane preparations contain a certain amount of lipid, so that treatments with --SH and --SS-- reagents could determine whether the fixation of the radioligand was to protein or to the lipid moiety. Pretreatment of CTX and CPU membranes with dithioerythritol, L-dithiothreitol, or 5,5'-dithiobis(2-nitrobenzoic acid), as well as with the alkylating agent N-ethylmaleimide, produced dose-dependent decreases of specific [3H]SCH23390 binding in membrane preparations from both tissues. These changes were not reversible after up to two washes, but could be prevented in part if the treatments were performed in the presence of dopamine. Additional protection experiments were conducted with (+)- and (-)-butaclamol, as well as with (+)- and (-)-SKF38393. A series of saturation experiments (with pretreated membranes in the absence of reactives) demonstrated that the alkylation of --SS-- groups reduced specific [3H]SCH23390 binding mainly through an affinity change, but L-dithiothreitol and 5,5-dithiobis(2-nitrobenzoic acid) decreased the number of binding sites. The affinity of the receptor to agonists was examined with the two enantiomers of SKF38393; the inhibition curves showed that residual binding was not affected and stereospecificity was conserved. The present results provide evidence for the participation of both --SS-- and --SH groups in the recognition site of the dopamine D1 receptor in both the CTX and the CPU.

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Direct and indirect effects of sulfhydryl blocking agents on agonist and antagonist binding to central α1- and α2-adrenoceptors

Cited by 22 publications

References 18 publications

p‐chloro‐mercuriphenyl sulphonate activates a quinine‐sensitive potassium conductance in frog lens.

p‐chloro‐mercuriphenyl sulphonate activates a quinine‐sensitive potassium conductance in frog lens.

Uncoupling of Rat Cerebral Cortical α₂‐Adrenoceptors from GTP‐Binding Proteins by N‐Ethylmaleimide

Specific [³H]SCH23390 Binding to Dopamine D₁ Receptors in Cerebral Cortex and Neostriatum: Role of Disulfide and Sulfhydryl Groups

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Direct and indirect effects of sulfhydryl blocking agents on agonist and antagonist binding to central α1- and α2-adrenoceptors

Cited by 22 publications

References 18 publications

p‐chloro‐mercuriphenyl sulphonate activates a quinine‐sensitive potassium conductance in frog lens.

p‐chloro‐mercuriphenyl sulphonate activates a quinine‐sensitive potassium conductance in frog lens.

Uncoupling of Rat Cerebral Cortical α2‐Adrenoceptors from GTP‐Binding Proteins by N‐Ethylmaleimide

Specific [3H]SCH23390 Binding to Dopamine D1 Receptors in Cerebral Cortex and Neostriatum: Role of Disulfide and Sulfhydryl Groups

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Product

Resources

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Uncoupling of Rat Cerebral Cortical α₂‐Adrenoceptors from GTP‐Binding Proteins by N‐Ethylmaleimide

Specific [³H]SCH23390 Binding to Dopamine D₁ Receptors in Cerebral Cortex and Neostriatum: Role of Disulfide and Sulfhydryl Groups