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  • 1
    Electronic Resource
    Electronic Resource
    Differential Binding Properties of Adenosine Receptor Agonists and Antagonists in Brain (1983)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 41 (1983), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The binding properties of N6-cydohexyl [3H]adenosine ([3H]CHA) and 1, 3-diethyl-8-[3H]phenyl-xanthine ([3H]DPX) in rat forebrain membrane are compared. The kinetic parameters of binding for each ligand are quite distinct, with [3H]CHA displaying two populations of binding sites (KD= 0.4 ± 0.05 nM and 4.2 ± 0.3 nM; Bmax= 159 ± 17 and 326 ± 21 fmol/mg protein), whereas [3H]DPX yielded monophasic Scatchard plots (KD= 13.9 ±1.1 nM;Bmax= 634 ± 27 fmol/mg protein). The metals copper, zinc, and cadmium are potent inhibitors of [3H]CHA binding, with respective IC50 concentrations of 36 [μM, 250 )μM, and 70 μM. Copper is a much less potent inhibitor of [3H]DPX binding (IC50= 350 μM). The inhibitory effect of copper on both [3H]CHA and [3H]DPX binding is apparently irreversible, as membranes pretreated with copper cannot be washed free of its inhibitory effect. The inhibitory effect of both copper and zinc on [3H]CHA binding was reversed by the guanine nucleotide Gpp(NH)p. [3H]DPX binding is only partially inhibited by zinc and cadmium (60% of specific binding remains unaffected), suggesting that this adenosine receptor ligand binds to two separate sites. Guanine nucleotides had no effect on the inhibition of [3H]DPX binding by either copper or zinc. Differential thermal and proteolytic denaturation profiles are also observed for [3H]CHA and [3H]DPX binding, with the former ligand binding site being more labile in both cases. Stereospecificity is observed in the inhibition of both [3H]CHA and [3H]DPX binding, with l-N-phenylisopropyladenosine (PIA) being 50-fold more potent than d-PIA in both cases. Evidence is therefore provided that adenosine receptor agonists and antagonists have markedly different binding properties to brain adenosine receptors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1983.tb04752.x
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  • 2
    Electronic Resource
    Electronic Resource
    The benzodiazepines and inosine antagonize caffeine-induced seizures (1981)
    Springer
    Psychopharmacology 72 (1981), S. 269-273 
    Details
    ISSN: 1432-2072
    Keywords: Caffeine ; Seizures ; Benzodiazepines ; Purines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The induction of generalized tonic-clonic seizures in mice by the methylxanthine stimulant caffeine is described. These seizures are indistinguishable in quality from those induced by pentylenetetrazol (PTZ), and pretreatment with low doses of caffeine potentiates PTZ-induced seizures. Benzodiazepines inhibit caffeine-induced seizures with a rank order potency that parallels their affinities for the central nervous system (CNS) benzodiazepine receptor in vitro. Inosine, a purine that has recently been shown to be a competitive inhibitor of [3H] diazepam binding in vitro, antagonizes caffeine-induced seizures, while 7-methyl-inosine, a purine that lacks receptor binding inhibitory activity, has no effect on seizures. Since the benzodiazepines, inosine, caffeine, and pentylenetetrazol all competitively inhibit [3H] diazepam binding and have marked effects on inducing or antagonizing seizures, further study of this receptor-ligand system may provide additional insights that concern possible biochemical mechanisms of seizures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00431829
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    Paper (German National Licenses)
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