Glutamate

Duce, I.R.

doi:10.1007/978-1-4615-9804-6_2

Cited by 8 publications

(6 citation statements)

References 164 publications

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“…Li + was a weak substitute, stimulating only 10% of the Lglutamate uptake seen in the presence of an equivalent concentration of Na +. A similar weak substitution may be seen in the high affinity L-glutamate uptake into body wall muscle of the blowfly Lucilia sericata, where replacement of Na + with Li + reduced glutamate uptake to 18% of control levels (Boden 1983, as cited in Duce 1988).…”

Section: Ionic Requirements For Glutamate Uptake Into the Epidermismentioning

confidence: 86%

“…With time, however, the epidermis transaminates glutamate and aspartate into nonneuroactive amino acids such as alanine, which then diffuse out of the cells (Tomlin et al 1993). Compared to other tissues with Na+/glutamate co-transporters, the beetle epidermis accumulates glutamate (on the basis of uptake per milligram tissue wet weight) at a rate almost 10-fold that of the cockroach CNS (Evans 1975) and many times more than the blowfly maggot muscle (Boden 1983, as cited in Duce 1988). Uptake into beetle CNS and skeletal muscle (Fig.…”

Section: Physiological Significance Of Co-transporter Kineticsmentioning

confidence: 96%

“…Na +-dependent high affinity transport of glutamate across the plasma membranes of neuronal (nerves and glia) and muscle tissue in arthropods is reported to require the presence of external Na + only (Duce 1988), whereas the transporter in vertebrate cells may have a co-requirement for K + (Schneider etal. 1980;Fukuhara and Turner 1985;Barbour et al 1988).…”

Section: Ionic Requirements For Glutamate Uptake Into the Epidermismentioning

confidence: 98%

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Na+-dependent medium-affinity uptake of L-glutamate in the insect epidermis

McLean

Caveney

1993

J Comp Physiol B

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Abstract.It is proposed that the activity of an epidermal cotransport system for Na § and dicarboxylic amino acids accounts for the small amounts of L-glutamate and L-aspartate in the otherwise amino-acid-rich blood plasma of insects. This Na+-dependent transport system is responsible for more than 95% of the uptake of these amino acids into the larval epidermis of the beetle Tenebrio molitor. Kinetic analysis of uptake showed that the Na+-dependent co-transporter has medium affinity for L-glutamate and L-aspartate. The K m for L-glutamate uptake was 146 gmol.1 1, and the maximum velocity of uptake (Fmax) was 12.1 pmol.mm -2 of epidermal sheet per minute. The corresponding values for L-aspartate were 191gmol'l 1 and 8.4pmol.mm-2.min -1. The Na+/L-glutamate co-transporter has a stoichiometry of at least two Na § ions for each L-glutamate-ion transported (n=217). The co-transporter has an affinity for Na + equivalent to a K m of 21 mmol.1-1 Na +. Na + is the only external ion apparently required to drive L-glutamate uptake. Li + substitutes weakly for Na +. Removal of external K + or addition of ouabain decreases uptake slowly over 1 h, suggesting that these treatments dissipate the Na+/K + gradient by inhibiting epidermal Na+/ K + ATPase. Several structural analogues of L-glutamate inhibit the medium-affinity uptake of L-glutamate. The order of potency with which these competitive inhibitors block glutamate uptake is L-cysteate_ threo-3-hydroxy-DL-aspartate > D-aspartate > L-aspartate > L-cysteine sulphinate > L-homocysteate ~> D-glutamate. L-trans-Pyrrolidine-2,4-dicarboxylate, a potent inhibitor of L-glutamate uptake in mammalian synaptosomes, is a relatively weak blocker of epidermal uptake. The epidermis takes Abbreviations: ac, acetate; Ch, choline; CNS, central nervous system; cpm, counts per minute; CDTA, trans-l,2-diaminocyclohexane-N,N,N',N'-tetraacetic acids; HPLC, high performance liquid chromatography; Kin, Michaelis constant; napp, apparent number; NMG, N-methyl-D-glucamine; Pipes; Piperazine-N,N'-bis-[2-ethanesulfonic acid]; SD, standard deviation; TEA, tetraethyl-ammonium; V, velocity of uptake; Vmax, maximum velocity of uptake Correspondence to: H. McLean up substantially more L-glutamate by this Na+-dependent system than tissues such as skeletal muscle and ventral nerve cord. The epidermis may be a main site regulating blood L-glutamate levels in insects with high blood [Na+]. Because L-glutamate and L-aspartate stimulate skeletal muscle in insects, a likely role for epidermal Lglutamate/L-aspartate transporter is to keep the level of these excitatory amino acids in the blood below the postsynaptic activation thresholds.

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Section: Ionic Requirements For Glutamate Uptake Into the Epidermismentioning

confidence: 86%

Section: Physiological Significance Of Co-transporter Kineticsmentioning

confidence: 96%

Section: Ionic Requirements For Glutamate Uptake Into the Epidermismentioning

confidence: 98%

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Na+-dependent medium-affinity uptake of L-glutamate in the insect epidermis

McLean

Caveney

1993

J Comp Physiol B

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Glutamate functions as a neurotransmitter in animals ranging from anemone, leech, earthworm, snail, squid and arthropods to mammals (Duce, 1988). In mammals, it is the predominant excitatory neurotransmitter in the central nervous system (CNS) (for a review, see Fonnum, 1984;Ottersen and Storm-Mathisen, 1984;Danbolt, 2001).

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mentioning

confidence: 99%

“…This is accomplished by cellular uptake catalysed by a family of sodium-and potassium-coupled glutamate transporters found in the plasma membranes of both neurons and glial cells (for reviews, see Danbolt et al, 1998a;Danbolt, 2001;Seal and Amara, 1999;Sims and Robinson, 1999). Five glutamate transporters, named excitatory amino acid transporters (EAAT) 1 to 5, have been identified in various mammalian tissues.Glutamate uptake has also been demonstrated in neural and neuromuscular tissues in arthropods (Duce, 1988). In insects, glutamate has been shown to be a transmitter in the CNS and at neuromuscular junctions (Faeder and Salpeter, 1970;…”

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confidence: 99%

Cellular distribution of a high-affinity glutamate transporter in the nervous system of the cabbage looperTrichoplusia ni

Gardiner

Ullensvang

Danbolt

et al. 2002

Journal of Experimental Biology

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SUMMARYGlutamate functions as a neurotransmitter in the central nervous system(CNS) and neuromuscular junctions in insects. High-affinity glutamate transporters are responsible for keeping the resting levels of excitatory amino acids below the synaptic activation threshold by removing them from the extracellular fluid, thereby preventing them from reaching toxic levels. Peptides representing the N- and C-terminal regions of a glutamate transporter cloned from the cabbage looper caterpillar (Trichoplusia ni) were synthesized and used to generate polyclonal antibodies. The antibodies produced immunohistochemical staining in both muscular and nervous system T. ni tissues. Neuromuscular junctions in the skeletal muscles produced the most intense labelling, but no visceral muscle or sensory nerves were labelled. In the CNS, the neuropile of the ganglia, but not the connectives, gave a diffuse staining. Electron microscopical examination of ganglia and neuromuscular junctions showed that the plasma membrane of glial cells, but not that of neurons was labelled, in agreement with the notion that most of the glutamate uptake sites in this insect are in glial cells.

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Glutamatergic Synthesis, Recycling, and Receptor Pharmacology at Drosophila and Crustacean Neuromuscular Junctions

Titlow

Cooper

2017

Neuromethods

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Glutamate

Cited by 8 publications

References 164 publications

Na+-dependent medium-affinity uptake of L-glutamate in the insect epidermis

Na+-dependent medium-affinity uptake of L-glutamate in the insect epidermis

Cellular distribution of a high-affinity glutamate transporter in the nervous system of the cabbage looperTrichoplusia ni

Glutamatergic Synthesis, Recycling, and Receptor Pharmacology at Drosophila and Crustacean Neuromuscular Junctions

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