Effect of K<sup>+</sup>‐stimulation on GABA metabolism in brain slices <i>in vitro</i>

Machiyama, Yukiteru; Balázs, R.; Richter, Derek

doi:10.1111/j.1471-4159.1967.tb09560.x

Cited by 45 publications

(17 citation statements)

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“…For example, it has been reported that net GABA formation in cortical slices increases following exposure of slices to elevated potassium (DUVILANSKI et a/., 1968). In addition, other investigators have concluded that GABA synthesis from glutamate in guinea-pig brain slices was approximately doubled by potassium depolarization (MACHIYAMA et al, 1967). However, the direct observation that GAD activity increases following in uitro depolarization is quite recent (GOLD et a/., 1978).…”

Section: Discussionmentioning

confidence: 98%

GLUTAMATE DECARBOXYLASE ACTIVITY IN STRIATAL SLICES: CHARACTERIZATION OF THE INCREASE FOLLOWING DEPOLARIZATION^1,²

Gold

Roth

1979

Journal of Neurochemistry

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Abstract— The activity of glutamate decarboxylase in rat striatal slices was estimated following preincubation in either a non‐depolarizing medium or in a depolarizing medium. GAD activity was significantly increased following preincubation in normal Krebs‐Ringer‐phosphate medium as compared to activity in slices which were not preincubated. GAD activity in slices which were depolarized in high potassium Krebs‐Ringer‐phosphate medium was further increased when compared to activity in slices which were preincubated in normal medium. The depolarization‐induced increase in GAD activity was graded in response to the time of depolarization, and both the increase following preincubation in normal medium and the increase following preincubation in high potassium displayed a relative requirement for calcium. In addition, net GABA formation from endogenous glutamate was increased in slices preincubated in high potassium medium as compared to net GABA formation from endogenous glutamate in slices preincubated in non‐depolarizing medium. In support of the use of [14C]CO2 trapping as an estimate of GAD activity in slices, preincubation of slices in the presence of the GAD inhibitor glutamic acid γ‐hydrazide caused a concentration‐related inhibition of [14C]CO2 evolution.

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Section: Discussionmentioning

confidence: 98%

GLUTAMATE DECARBOXYLASE ACTIVITY IN STRIATAL SLICES: CHARACTERIZATION OF THE INCREASE FOLLOWING DEPOLARIZATION^1,²

Gold

Roth

1979

Journal of Neurochemistry

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“…Elevated external potassium concentrations have also been shown to increase the release from brain slices of noradrenaline (Baldessarini & Kopin, 1967); GABA (Machiyama, Balazs & Richter, 1967;Srinivasan et al, 1969;Leach, 1979), D-aspartate (Davies & Johnston, 1976), glycine (Hopkin & Neal, 1971) and taurine (Kaczmarek & Davison, 1972). Evidence that the release of [3H]-spermine from brain slices is not due to an indiscriminate increase in membrane permeability is indicated by the inability of high potassium concentrations to evoke the release of f14C]urea.…”

Section: Discussionmentioning

confidence: 99%

THE SPONTANEOUS AND EVOKED RELEASE OF SPERMINE FROM RAT BRAIN in vitro

Harman

Shaw

1981

British J Pharmacology

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The efflux of previously accumulated [3H]‐spermine from brain slices was measured using a continuous perfusion system. The spontaneous efflux was biphasic, consisting of an initial rapid efflux followed by a much slower release. The slices were depolarized by the addition to the medium of high potassium concentrations, ouabain or veratrine. At concentrations greater than 30 mM, potassium evoked a striking increase in the release of [3H]‐spermine. Following uptake in the presence of 5.7 × 10−9M[3H]‐spermine, K+‐evoked release was dependent on the presence of calcium ions. Release of spermine after uptake at 5.6 × 10−8m or 5.0 × 10−7m was not calcium‐dependent. The calcium‐dependent, K+‐stimulated release of spermine was inhibited in the presence of diphenylhydantoin (5 × 10−3m) or ruthenium red (10−3 m). Following uptake of 5.7 × 10−9m [3H]‐spermine in a sodium‐free medium, the calcium‐dependent, K+‐stimulated release was significantly inhibited. Ouabain (10−4m) caused a large but calcium‐independent increase in the efflux of [3H]‐spermine. Veratrine‐induced release was less substantial but was increased in a calcium‐free medium. Release evoked by veratrine was abolished in the absence of sodium. These results are discussed with respect to a possible ‘neurotransmitter’ or ‘neuromodulator’ role for spermine.

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“…The effluxes of C3H]glycine, C3H]alanine and C3H]leucine were all more rapid than that of C3H]GABA, and this possibly reflects the different cellular distributions of these exogenous amino acids Table 1 ; the concentration of each amino acid in the incubation medium is also indicated in Table 1 The rate of release of C3H]GABA could be increased by exposing the ganglia to high concentrations of potassium, a procedure which has also been shown to release C3H]GABA from brain slices (SRINIVASAN et al, 1969;ARNFRED & HERTZ, 1971;MACHIYAMA et al, 1967) and synaptosomes (DE BELLEROCHE & BRAD-FORD, 1972). Uptake of C3H]GABA in slices or homogenates of rat brain, however, occurs principally into nerve terminals or synaptosomes (IVERSEN & BLOOM, 1972;HBKFELT & LJUNGDAHL, 1970); in brain slices raising the extracellular potassium concentration has been shown to depolarize cells that because of their low resting potential were probably neurones (HILL- MAN & MCILWAIN, 1961).…”

Section: Metabolism Experimentsmentioning

confidence: 99%

RELEASE OF [³H]GAMMA‐AMINOBUTYRIC ACID FROM GLIAL CELLS IN RAT DORSAL ROOT GANGLIA.

Minchin

Iversen

1974

Journal of Neurochemistry

195

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Abstract— Desheathed rat dorsal root ganglia were incubated in a medium containing amino‐oxyacetic acid and [3H]GABA. Under these conditions, [3H]GABA is taken up exclusively by the satellite glial cells in the ganglia. Efflux of [3H]GABA from the tissue was measured after passing the ganglia through a series of wash solutions. The spontaneous efflux of radioactivity, mostly [3H]GABA, was more rapid in the absence of amino‐oxyacetic acid in the incubation and wash media. Raising the potassium concentration in the wash media caused an increase in the efflux of [3H]GABA. This increase was sigmoidally related to the potassium concentration in the wash media, reaching a maximum at 64 mm‐K+. The releasing effect of K+ was inhibited by removing calcium from the media. Reducing the calcium and raising the magnesium concentration in the wash solutions inhibited the increased efflux of [3H]GABA due to 64 mm‐K+ by 48 per cent, while 5 mM‐La3+ and diphenylhydantoin (0·005 and 0·5 mm) had no effect on this increase. Only a small increase in the efflux of [14C]glutamate was produced by 64 mm‐K+ and it had no effect upon the effluxes of [3H]glycine, [3H]alanine or [3H]leucine. The efflux of lactate dehydrogenase was similarly unaffected by 64 mM‐K+. The results suggest that glial cells in spinal ganglia can respond to depolarizing concentrations of potassium by releasing GABA in a calcium‐dependent process.

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Effect of K⁺‐stimulation on GABA metabolism in brain slices in vitro

Cited by 45 publications

References 2 publications

GLUTAMATE DECARBOXYLASE ACTIVITY IN STRIATAL SLICES: CHARACTERIZATION OF THE INCREASE FOLLOWING DEPOLARIZATION^1,²

GLUTAMATE DECARBOXYLASE ACTIVITY IN STRIATAL SLICES: CHARACTERIZATION OF THE INCREASE FOLLOWING DEPOLARIZATION^1,²

THE SPONTANEOUS AND EVOKED RELEASE OF SPERMINE FROM RAT BRAIN in vitro

RELEASE OF [³H]GAMMA‐AMINOBUTYRIC ACID FROM GLIAL CELLS IN RAT DORSAL ROOT GANGLIA.

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Effect of K+‐stimulation on GABA metabolism in brain slices in vitro

Cited by 45 publications

References 2 publications

GLUTAMATE DECARBOXYLASE ACTIVITY IN STRIATAL SLICES: CHARACTERIZATION OF THE INCREASE FOLLOWING DEPOLARIZATION1, 2

GLUTAMATE DECARBOXYLASE ACTIVITY IN STRIATAL SLICES: CHARACTERIZATION OF THE INCREASE FOLLOWING DEPOLARIZATION1, 2

THE SPONTANEOUS AND EVOKED RELEASE OF SPERMINE FROM RAT BRAIN in vitro

RELEASE OF [3H]GAMMA‐AMINOBUTYRIC ACID FROM GLIAL CELLS IN RAT DORSAL ROOT GANGLIA.

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Effect of K⁺‐stimulation on GABA metabolism in brain slices in vitro

GLUTAMATE DECARBOXYLASE ACTIVITY IN STRIATAL SLICES: CHARACTERIZATION OF THE INCREASE FOLLOWING DEPOLARIZATION^1,²

GLUTAMATE DECARBOXYLASE ACTIVITY IN STRIATAL SLICES: CHARACTERIZATION OF THE INCREASE FOLLOWING DEPOLARIZATION^1,²

RELEASE OF [³H]GAMMA‐AMINOBUTYRIC ACID FROM GLIAL CELLS IN RAT DORSAL ROOT GANGLIA.