Modulation of GABA flux across rat brain membranes resolved by a rapid quenched incubation technique
| Autor: | Julianna Kardos, Ilona Kovács, Tamás Blandl, Derek J. Cash |
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| Rok vydání: | 1994 |
| Předmět: |
Male
Time Factors Biology GABA Antagonists chemistry.chemical_compound Reaction rate constant Methods Animals Neurotransmitter Uptake Inhibitors Rats Wistar Neurotransmitter Incubation gamma-Aminobutyric Acid General Neuroscience Vesicle Cell Membrane Brain Depolarization Transporter Biological Transport Rats Membrane chemistry Biochemistry Biophysics Potassium Calcium Efflux |
| Zdroj: | Neuroscience letters. 182(1) |
| ISSN: | 0304-3940 |
| Popis: | The progress and inhibition of [3H]GABA influx in native plasma membrane vesicles from the rat cerebral cortex was studied on a subsecond to minute time scale under different conditions by applying a rapid quenched incubation technique. In the absence of Ca2+ ([Ca2+]free = 10−8 M), the progress of influx followed by the addition of 10 nM [3H]GABA to the membrane vesicle suspension with time (500 ms to 15 min) can be described by a first-order rate equation giving an overall rate constant, k, of 3.93 ± 0.48 × 10−3 s−1 and equilibrium influx value, INFe, of 8.84 ± 0.41 pmol [ 3 H]GABA/mg protein . In the presence of Ca2+ ([Ca2+]free = 2.4 × 10−3 M) a significant increase in the INFe value was observed (k = 4.64 ± 0.41 × 10−3 s−1 and INF e = 13.9 ± 0.40 pmol [ 3 H]GABA /mg protein ). Multiplicity of GABA transporters was indicated in the time-dependent inhibition of [3H]GABA influx by different uptake blockers. In the absence of Ca2+, depolarization (75 mM KCl) inhibited the influx of [3H]GABA into the vesicles by ∼70% and initiated the efflux from vesicles loaded with [3H]GABA. Different uptake blockers inhibited the Ca2+-independent translocation of [3H]GABA in both directions with similar specificities. |
| Databáze: | OpenAIRE |
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