Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: CAS:6893-26-1 (glutamate)
 73,096 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cryptococcus albidus utilizes glutamate as a sole carbon source. The kinetics of uptake of this amino acid were studied. l-Glutamic acid was taken up by two saturable systems: a high affinity system with a Michaelis constant (K(m)) of 1.15 x 10(-5) M and a V(max) of 0.049 mumol per mg per h and a low affinity system with a K(m) of 2.5 x 10(-3) M and a V(max) of 3.61 mumol per mg per h. Both systems possessed characteristics of active transport which were dependent on temperature and pH and which required metabolic energy. Uptake was inhibited at 37 C but the temperature-sensitive step was reversible. Chemical fractionation of cells with 5% trichloroacetic acid showed that glutamic acid initially entered a soluble pool which decreased after 1 h as the amino acid was incorporated into the protein and nucleic acid fractions of the yeast. Some of the glutamate was completely oxidized and could be recovered as (14)CO(2). Therefore, the amino acid was also used as an energy source.
 ...
PMID:Uptake and utilization of glutamic acid by Cryptococcus albidus. 471 25

The experiments were carried out to find out whether exogenous glutamic or aspartic acid could diminish changes in the cardiac contractile function and high-energy phosphate content caused by underperfusion of isolated isovolumic rat heart. After 40 min of reduced coronary flow (from 10 to 3 ml/min) there was an almost four-fold fall in the developed pressure, and more than three-fold rise in the diastolic pressure as well as a profound fall in creatine phosphate (CP) and ATP content. Glutamic (68 mM) or aspartic (75 mM) acids were added to the perfusate after 10 min of underperfusion when the developed pressure had declined almost to the same level as was observed after 40 min and the content of CP was reduced more than two-fold. Glutamic acid completely prevented the rise in the diastolic pressure and significantly increased the CP content, as compared to its level observed before addition of glutamate, but glutamic acid did not change the developed pressure. As a result, the CP and ATP contents were three- and two-fold higher, respectively, after addition of glutamic acid as compared to control underperfused hearts. Similar, but slightly less prominent effects were observed when aspartic acid was added instead of glutamic acid. These results suggest that high concentrations of glutamic and aspartic acids can exert beneficial effects on ischemic heart muscle.
 ...
PMID:Effect of glutamic and aspartic acids on adenine nucleotides, nitrogenous compounds and contractile function during underperfusion of isolated rat heart. 613 4

Glutamic acid may protect the ischemic myocardium by increasing the flux through anaerobic pathways for ATP production. We tested this in isolated rabbit hearts that were treated with 0 or 2 mM glutamate. Hearts were stabilized for 30 min, subjected to ischemia for 30 min, and then reperfused for 30 min. Cardiac performance was defined by measuring peak left ventricular pressure (PLVDP) at the apex of a Starling curve and expressed as the %PLVDP attained during the preischemia period. Glutamate improved cardiac performance (%PLVDP, treated vs. untreated) after moderate ischemia (92 vs. 67), severe ischemia (79 vs. 65), and total ischemia (61 vs. 41). During severe ischemia, improved performance was associated with enhanced release (nmol X g wet wt -1 X min -1, treated vs. untreated) of alpha-ketoglutarate (2.3 vs. 1.3), succinate (21.7 vs. 12.3), and lactate (478 vs. 386). The ischemic myocardial content (nmol/mg myocardial protein, treated vs. untreated) of alpha-ketoglutarate (1.7 vs. 1.2) was increased by glutamate. The ischemic content of ATP (25.4 vs. 21.9) and succinate (15.7 vs. 12.1) showed a slight trend toward improvement under glutamate treatment. The study shows an association between improved postischemic cardiac performance and increased production of alpha-ketoglutarate and succinate during glutamate treatment.
 ...
PMID:Protection of ischemic rabbit myocardium by glutamic acid. 613 48

L-Glutamate (in 0.1 microliter of 0.9% NaCl) was injected via multibarrelled glass micropipettes into the ventrolateral medulla of urethane-anesthetized rats. This area, explored stereotaxically, extended from 2.2 mm rostral (near trapezoid bodies) to 0.4 mm caudal, with respect to the obex, 2.4 mm lateral to the mid-line on each side and 2.4 mm deep from the ventral surface of the medulla. Two types of responses were elicited by injection of L-glutamate. One type was a dose-related increase in arterial pressure and heart rate; these responses were elicited from the lateral portion of nucleus reticularis gigantocellularis, the medial aspect of nucleus reticularis parvocellularis and the dorsal-lateral reticular nucleus. The second type of response was a dose-related fall in arterial pressure with no change in heart rate; this response was localized caudal to pressure areas in the caudal ventrolateral part of nucleus reticularis gigantocellularis, ventrolateral nucleus reticularis ventralis, nucleus ambiguous and the A1 region. Glutamic acid diethylester (GDEE), an antagonist of L-glutamate, blocked all the cardiovascular effects of L-glutamate. These results indicate the presence of receptors for glutamate in the pressor and depressor areas. Glutamic acid diethylester caused a fall in blood pressure when injected on its own into pressor sites suggesting the existence of a glutaminergic input to the pressor sites. Inhibition of neuronal activity in pressor sites produced by microinjection of muscimol (a potent neuroinhibitory analogue of GABA) caused a decrease in blood pressure. On the other hand, pressor responses resulted following similar inhibition in the depressor sites. These results indicate that the pressor and depressor sites identified in the ventral medulla of the rat may have an important role to play in central cardiovascular regulation.
 ...
PMID:Vasopressor and depressor areas in the rat medulla. Identification by microinjection of L-glutamate. 613 27

Effects of glutamic, aspartic, and cysteic acid, and of kainic acid and N-methyl aspartate on the release of labeled GABA, glycine, and taurine were examined in isolated, perfused chick retina. Glutamic acid (0.5-2 mM), increased the release of 3H-GABA by more than four times and that of 14C-glycine by about two times. The release of GABA decreased 50% and that of glycine 95% in the presence of the antagonist of glutamic acid receptors, glutamate diethyl ester (300 microM). N-methyl aspartate, used as an agonist of aspartic acid receptors, preferentially increased the release of GABA (seven times) over that of glycine (three times). The stimulatory effect of N-methyl aspartate was antagonized by D-alpha-aminoadipate and by Mg. Kainic acid (10 microM) induced the release of glycine but not that of GABA. Cysteic acid failed to modify the release of any of the amino acids examined. The efflux of labeled taurine was practically unaffected by all the compounds utilized. The release of GABA by the excitatory amino acids and agonists was Ca-independent but Na-dependent, whereas the release of glycine was markedly Ca-dependent. The evidence presented here suggests that experimental conditions activating receptors of excitatory amino acids differently affect the release of inhibitory amino acids.
 ...
PMID:Effects of excitatory amino acids, and of their agonists and antagonists on the release of neurotransmitters from the chick retina. 613 87

The subcellular distribution of kainic acid (KA) binding sites in rat brain has been studied using a microcentrifugation assay. KA did not bind to myelin or brain cytosol and had few or no binding sites in the nuclear fraction. However, it bound to microsomal components (Kd = 128-136 nM; 2.5-4.8 pmol/mg protein), purified synaptic plasma membranes (SPM)(Kd = 45-71 nM; 5.8-6.5 pmol/mg), and purified cell-body and intraterminal mitochondria (Kd = 11-31 nM; 0.4-1.1 pmol/ng). Bound KA could be totally displaced by L-glutamate or L-asparate, but several putative antagonists of these amino acids (nuciferin, compound HA-966, 2-amino-4-phosphonobutyrate, and 2-amino-3-phosphonoproprionate) failed to displace KA or did so at very high concentrations (greater than or equal to 4 mM). Glutamic acid diethyl ester (GDEE) and D,L-alpha-aminoadipate (alpha-AA) were more effective (IC50, 0.2-0.8 mM) and showed differential effects in their capacity to displace KA bound to the various subcellular fractions. Thus, GDEE only displaced 40-60% of the KA bound by SPM or mitochondria and did not prevent the binding of KA to microsomes. alpha-AA, on the other hand, was more effective in preventing the binding of KA at high concentrations and displaced between 80 and 100% of the drug. Both compounds showed biphasic curves of KA displacement from synaptic plasma membranes and mitochondria. The overall results indicate the presence of multiple binding sites for KA in brain cells and suggest that KA does not act exclusively as synaptic glutamate receptors. The mechanism of KA action is most likely quite complex, and the drug probably acts at multiple binding sites affecting a number of processes.
 ...
PMID:Specific binding of kainic acid to purified subcellular fractions from rat brain. 625 92

A physiological and pharmacological investigation of a novel endogenous excitant, quinolinic acid, was carried out in male rats using conventional iontophoretic techniques. It was established that quinolinic acid responses were preferentially reduced by antagonists acting at the N-methyl-D-aspartate (NMDA) preferring receptor, such as (+/-)-2-amino-7-phosphono-heptanoic acid and 1-hydroxy-3-amino-pyrrolidone-2. Glutamic acid diethyl ester reduced responses to quinolinic acid, quisqualic acid and NMDA with no clear specificity. Streptomycin, thought to act at the quisqualic acid receptor, largely spared quinolinic acid responses, being more effective against quisqualic acid evoked excitations. It is therefore suggested that quinolinic acid acts primarily at the NMDA receptor. In addition, the sensitivity of various components of the neuraxis to quinolinic acid was assessed and compared with glutamate and NMDA. Neurons in the spinal cord and cerebellum were largely unresponsive to quinolinate, whereas cells in the neocortex, striatum and hippocampus responded to this agonist to a similar degree as glutamate. In the cortex quinolinate was about one-fifth as active as NMDA, which together with quinolinic acid was much less active in the spinal cord and cerebellum. It is concluded that the possibility that quinolinic acid has a neurotransmitter type function at central "amino acid" receptors merits further investigation.
 ...
PMID:Pharmacology and regional variations of quinolinic acid-evoked excitations in the rat central nervous system. 630 11

Glutamic acid is synthesized in enteric bacteria by either glutamate dehydrogenase or by the coupled activities of glutamate synthase and glutamine synthetase. A hybrid plasmid containing a fragment of the Salmonella typhimurium chromosome cloned into pBR328 restores growth of glutamate auxotrophs of S. typhimurium and Escherichia coli strains which have mutations in the genes for glutamate dehydrogenase and glutamate synthase. A 2.2-kilobase pair region was shown by complementation analysis, enzyme activity measurements, and the maxicell protein synthesizing system to carry the entire glutamate dehydrogenase structural gene, gdhA. Glutamate dehydrogenase encoded by gdhA carried on recombinant plasmids was elevated 5- to over 100-fold in S. typhimurium or E. coli cells and was regulated in both organisms. The gdhA promoter was located by recombination studies and by the in vitro fusion to, and activation of, a promoter-deficient galK gene. Additionally, S. typhimurium gdhA DNA was shown to hybridize to single restriction fragments of chromosomes from other enteric bacteria and from Saccharomyces cerevisiae.
 ...
PMID:Cloning and characterization of gdhA, the structural gene for glutamate dehydrogenase of Salmonella typhimurium. 636 Sep 94

Glutamic acid diethyl ester (GDEE), a putative antagonist of glutamate-induced neuronal excitations, was administered prior to an instrumental conditioning task motivated by food reinforcement. A profound impairment of learning was produced in animals receiving 240 or 480 mg/kg of GDEE. Performance was not impaired by GDEE in rats that had previously learned the task. These findings support suggestions that central excitatory processes play an important role in learning phenomena, in particular when these learning phenomena involve acquisition of new behavioral patterns.
 ...
PMID:Impairment of instrumental learning in rats by glutamic acid diethyl ester. 720 61

L-[3H]Glutamic acid binds reversibly to rat brain membranes with high affinity. Specific binding is linear with tissue concentration and has a pH optimum at neutrality. Saturation isotherms reveal anomolous kinetics of specific binding with an high affinity site with a KD of 11 nM and a lower affinity site with a KD of 80 nM; the Scatchard plots intercept at a common bound/free ratio. Hill plots of the complete saturation isotherms have a slope of 1.0. There are marked regional differences in the distribution of binding sites in rat brain: parietal cortex, frontal cortex, hippocampus greater than striatum greater than thalamus greater than cerebellum, pons-medulla and hypothalamus. Except for a small amount of specific binding in heart, other peripheral tissues do not exhibit specific binding of L-[3H]glutamic acid. Several amino acids with neuroexcitatory effects inhibit the specific binding: L-glutamic acid greater than L-aspartic acid and D,L-homocysteic acid greater than D-glutamic acid and L-cysteine sulfinic acid; related amino acids without neuroexcitatory effects do not inhibit specific binding. Reputed antagonists of glutamate-induced neuronal depolarization block specific binding: alpha-aminoadipic acid greater than 2-amino,4-phosphonobutyric acid greater than glutamate diethylester. Prior kainate lesion of the neurons intrinsic to the striatum results in a 45% decrement in specific binding of L-[3H]glutamic acid whereas cortical ablation, which causes degeneration of a cortical-striatal glutamatergic projection and reduces striatal glutamate synaptosomal uptake, does not affect specific binding. These results are compatible with the interpretation that the binding of [3H]glutamic acid occurs at excitatory receptors on neurons.
 ...
PMID:Characterization of specific, high-affinity binding sites for L-[3H]glutamic acid in rat brain membranes. 735 47


<< Previous 1 2 3 4 5 6 7 8 Next >>