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Digitale Medien

Characterization of the GABA-lnduced Current in Frog Pituitary Melanotrophs (1994)

Louiset, E. ; Mei, Y. A. ; Valentijn, J. A. ; [weitere]

Oxford, UK : Blackwell Publishing Ltd

Journal of neuroendocrinology 6 (1994), S. 0

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ISSN: 1365-2826

Quelle: Blackwell Publishing Journal Backfiles 1879-2005

Thema: Medizin

Notizen: The molecular mechanisms regulating GABAA receptor activity in cultured frog melanotrophs were studied using the patch-clamp technique. In the whole-cell configuration, application of GABA evoked a dose-related increase of inward chloride currents. The ED50 value, estimated from the sigmoidal dose-response curve was 2 × 10−6 M and the Hill coefficient was 1.55. The amplitude of the GABA-induced current decayed with time. Kinetics analysis of the desensitization revealed that the time-course of the current decrement was fitted by one exponential. Graded doses of GABA or association of GABA with the benzodiazepine receptor agonist flunitrazepam accelerated the desensitization process. In contrast, the time-course of the current did not significantly vary at different holding potentials. In the outside-out configuration, GABA was found to activate channels which displayed three unitary conductance levels (8, 15 and 30 pS). The channel openings of the more frequent conductance level (30 pS) exhibited short and long lasting open states (1.2 and 28.3ms at -60mV). Altogether these data reveal that frog melanotrophs possess a single population of GABAA receptors which interconvert into a higher affinity state in the presence of benzodiazepine receptor agonists. Two GABA molecules must bind to the receptor to trigger long lasting channel openings. In addition, the activity of the GABAA receptor appears to be independent of the accumulation of intracellular chloride ions.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1111/j.1365-2826.1994.tb00553.x

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Digitale Medien

Global energy spectra of bands and density of states in a class of two-tile systems (1994)

Yan, X. H. ; Yan, J. R. ; You, J. Q. ; [weitere]

Springer

The European physical journal 94 (1994), S. 439-446

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ISSN: 1434-6036

Schlagwort(e): 71.25.Cx ; 61.42.+h ; 71.25.-s

Quelle: Springer Online Journal Archives 1860-2000

Thema: Physik

Notizen: Abstract Electronic properties of a general class of one-dimensional two-tile systems are calculated exactly. The systems containing periodic crystals, generalized Fibonacci quasicrystals, generalized Thue-Morse aperiodic lattices and even other two-tile aperiodic lattices, can be divided into two different families which are constructed by the inflation rules: {A, B}→{A m11 B m12,A m21 B m22} and {A, B}→{A n11 B n12,B n21 A n22}, respectively. As typical examples, global spectra of bands and density of states in some two-tile aperiodic systems are numerically calculated. Some interesting properties are obtained.