Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.6.1.2 (alanine aminotransferase)
 26,722 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Growth of a highly-deviated ascites hepatoma (Yoshida AH-130) in rats caused initial hyperplastic enlargement of the liver, followed by progressive reduction to a size lower than that seen in controls. The time-course of this biphasic change in liver weight roughly corresponded to the exponential and stationary phases of tumour growth. Histologically, scattered small foci of perilobular necrosis were observed during the hyperplastic phase and these were consistently associated with a moderate elevation of glutamate-pyruvate transaminase (GPT) activity in the blood plasma. By contrast, signs of necrosis were absent and plasma GTP levels had returned to normal during the phase of hepatic involution, which was characterized by enhanced apoptosis, a type of single-cell death known to be involved in the regulation of tissue size under both normal and pathological conditions. Biochemically, alterations in liver protein mass resulted from changed rates of tissue protein degradation. The apoptotic bodies could either be lost from the liver via blood, lymph and bile, or phagocytosed and degraded by adjacent cells. Disposal of the apoptotic bodies is likely to account, at least in part, for the enhanced rates of liver protein turnover that characterize hepatic involution.
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PMID:Regulation of cell turnover in the livers of tumour-bearing rats: occurrence of apoptosis. 279 40

To study the role of lipid peroxidation in halothane-induced hepatic damage, ethane exhalation by rats exposed to 1% halothane for 1 hour was determined under normoxic (21% O2) and hypoxic (6% O2) conditions. The effects of microsomal enzyme induction by phenobarbital and/or glutathione depletion on this parameter of in vivo lipid peroxidation were studied. To assess the degree of liver damage, serum activities of liver specific enzymes (glutamate-pyruvate-transaminase, GPT, and sorbitol dehydrogenase, SDH) were measured 3 hrs after the end of exposure. Besides, liver content of thiobarbituric acid-reactive material was estimated as a further parameter of lipid peroxidation. Enhanced rates of lipid peroxidation over basal levels were only seen under conditions leading to hepatic damage, i.e. phenobarbital induction and hypoxia. The highest rate of lipid peroxidation was observed after depletion of hepatic glutathione in addition to microsomal enzyme induction and hypoxia. Deferrioxamine, diethyldithiocarbamate and (+)-catechin inhibited in vivo lipid peroxidation, but only (+)-catechin suppressed halothane-hepatoxicity. These results indicate that halothane-induced hepatic damage is associated with an enhanced rate of lipid peroxidation, but this might not be the only mechanism of halothane toxicity.
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PMID:Enhanced in vivo-lipid peroxidation associated with halothane hepatotoxicity in rats. 284 Jun 50

Food intake, plasma and brain amino acid concentrations, liver amino acid catabolic enzyme activities, and whole-brain neurotransmitter and metabolite concentrations were measured in young rats adapted for 11 d to diets containing from 5 to 75% (in increments of 5%) casein. Food intake was depressed initially in rats fed diets containing 5, 10% or greater than 35% casein. For the duration of the experiment, food intakes of the groups fed the higher protein diets improved on successive days; the length and severity of the depression were proportional to the protein content of the diet fed. Rats fed low levels of protein grew poorly, and their food intake remained depressed. The gradual improvement in growth and food intake of rats fed diets containing more than 35% casein was accompanied by dramatic increases in the activities of serine-threonine dehydratase (SDH, EC 4.2.1.16) and glutamate-pyruvate aminotransferase (GPT, EC 2.6.1.1) in liver. The increase in amino acid catabolic activity was accompanied by decreases in the concentrations of most amino acids in plasma and brain. However, concentrations of branched-chain amino acids, in both plasma and brain, increased in direct proportion to the protein concentration of the diet fed. As a result of these reciprocal responses, the total concentration of indispensable amino acids in brain (IAA) was maintained within a narrow range of values, despite a sixfold range of protein intakes. Whole-brain concentrations of norepinephrine, dopamine and serotonin were not correlated with dietary protein concentration, total food intake or protein intake. Brain concentrations of homovanillic acid and 5-hydroxyindoleacetic acid were correlated inversely with protein intake and that of 3,4-dihydroxyphenylacetic acid was correlated directly with food intake. Protein intake appeared to be related to the animal's ability to maintain brain total IAA content between some upper and lower limits. Our results indicate that this was accomplished initially through downward adjustment of protein intake and subsequently through an increase in catabolic capacity for the amino acids.
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PMID:Adaptation of rats to diets containing different levels of protein: effects on food intake, plasma and brain amino acid concentrations and brain neurotransmitter metabolism. 285 80

Alterations in microsomal drug metabolizing enzymes, microsomal lipids and some serum enzymes following pre-treatment of rats with therapeutic doses of four structurally different antimalarial compounds, chloroquine (CQ), quinine (Q), quinacrine (QK) and primaquine (PQ) have been investigated. CQ and Q significantly decreased the activities of aminopyrene N-demethylase, aniline hydroxylase and both microsomal and cytosolic glutathione S-transferases. Only aniline hydroxylase was markedly decreased by QK, while PQ did not have much effect on any of these enzymes. CQ, Q and QK significantly increased the cholesterol:phospholipid ratio while all four compounds decreased the phosphatidyl choline:sphingomyelin (PC/S) ratio. All the drugs increased the activities of the serum enzymes glutamate-oxaloacetate transaminase, glutamate-pyruvate transaminase and alkaline phosphatase. The possible relationships of these results to structural variations in the four drugs being investigated has been discussed.
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PMID:Drug induced alterations in some rat hepatic microsomal components: a comparative study of four structurally different antimalarials. 286 Oct 39

In vivo studies were performed in the dog to verify if sodium lactate had an important effect on the metabolism of glutamine by the kidney. The animals were infused with 0.6 M sodium lactate to induce acute metabolic alkalosis with plasma bicarbonate of 29.7 mM. During these experiments, it was demonstrated that the renal uptake of glutamine increased by 46%, while the renal production of ammonia was unchanged. The renal production of alanine rose from 6.0 to 16.8 mumol/min. Plasma concentration of lactate increased from 1.3 to 19.2 mM, while that of pyruvate increased from 0.075 to 0.454 mM. In the renal tissue, alpha-ketoglutarate, malate, oxaloacetate, lactate, pyruvate, citrate, and alanine increased significantly. Similar changes were found in the liver and skeletal muscle. The observed changes are best described by transamination of pyruvate and glutamate under the influence of alanine aminotransferase (GPT). It can be calculated that this reaction was responsible for 76% of the production of ammonia from glutamine, the latter being necessary to provide glutamate for the synthesis of alanine. Dogs infused with 0.3 M sodium bicarbonate instead of sodium lactate with the same degree of acute metabolic alkalosis, showed a depression of 40% in the renal uptake of glutamine with a 38% decrease in renal ammoniagenesis and a 20% fall in the production of alanine. The present studies demonstrate that the production of ammonia from glutamine is not necessarily related to changes in acid-base balance, but may be associated with biochemical alterations related to the synthesis of alanine by the kidney.
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PMID:The metabolic response of the kidney to acute sodium lactate alkalosis. 286 25

Using analytical subcellular fractionation techniques, 12% of the total L-alanine aminotransferase activity and 26% of the total L-aspartate aminotransferase activity was localized in enterocyte mitochondria. Alanine and aspartate were products from the oxidation of glutamine and glutamate by enterocyte mitochondria. At low concentrations, malate stimulated aspartate synthesis but was inhibitory at higher concentrations. The malate inhibition of aspartate synthesis, which increased in the presence of pyruvate, was accompanied by an increase in alanine synthesis. With glutamine as substrate in the presence of pyruvate and malate, alanine synthesis was increased by 127% on addition of purified L-alanine aminotransferase, in spite of large amounts of glutamate generated. It was concluded that when pyruvate is available the important route for glutamine or glutamate oxidation by transamination was via L-alanine:2-oxoglutarate aminotransferase and not via L-aspartate:2-oxoglutarate aminotransferase. Results suggested that mitochondria may account for 50% of alanine production from glutamine in the enterocyte despite the relatively low activity of L-alanine aminotransferase therein.
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PMID:Transamination pathways influencing L-glutamine and L-glutamate oxidation by rat enterocyte mitochondria and the subcellular localization of L-alanine aminotransferase and L-aspartate aminotransferase. 286 79

Amino acids of the glutamate family, viz. glutamic acid, aspartic acid, glutamine, gamma-amino-butyric acid (GABA) and alanine, along with the activities of glutamic acid dehydrogenase (GDH), aspartic acid aminotransferase (AST), alanine aminotransferase (ALT), glutamine synthetase (GS), glutaminase, glutamic acid decarboxylase (GAD) and GABA-aminotransferase (GABA-T) were estimated in cerebral cortex, cerebellum and brain stem of rats treated with a single dose of lithium or with seven daily doses of lithium (3 m-equiv./kg body wt). The levels of GABA were found to increase in cerebral cortex and brain stem following the administration of a single dose and also were found to be increased in cerebral cortex and cerebellum after treatment for 7 days. The content of glutamic acid was increased in all three brain regions after treatment for 7 days. Glutamine was increased in both cerebral cortex and brain stem after treatment for 7 days, whereas aspartic acid was increased in brain stem after both the administration of single dose and treatment for 7 days. A significant increase (P less than 0.05) in the activity of GS was observed in brain stem after 7 days of treatment. Similarly, a significant increase (P less than 0.01) in the activity of AST was observed in all three regions of the brain following the treatment for 7 days. The above results are discussed in relation to the known effects of lithium on brain cation metabolism and a suggestion is made that an imbalance in the functional activities of glutamic acid and GABA as a result of quantitative changes in these amino acids, brought about by lithium, may play a role in the therapeutic efficacy of lithium in bipolar disorders.
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PMID:Acute and short-term effects of lithium on glutamate metabolism in rat brain. 286 24

Activity of enzymes participating in metabolism of glutamate and content of nicotinamide nucleotides was studied in rat liver tissue within 24 hrs after intramuscular administration of alpha-tocopheryl acetate at doses of 30 mg and 300 mg per kg of body mass. Excess of the vitamin was responsible for a decrease in the ratio NAD+/NADH in cytosol, for stimulation of glutamate dehydrogenase reaction, for a decrease of aspartate aminotransferase activity in mitochondria and of alanine aminotransferase activity in cytosol as well as for an increase of NADPH content.
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PMID:[Effect of alpha-tocopherol on glutamic acid metabolism and nicotinamide coenzyme levels in hepatocytes]. 287 84

6-Aminonicotinamide (6-AN), an antimetabolite of pyridine nucleotide synthesis, caused time dependent and regionally selective changes in the activities of the enzymes related to glutamate metabolism in the brain. The NAD+- and NADP+-linked glutamate dehydrogenase showed opposite pattern of changes in cerebellum, whereas cerebral hemispheres and brain stem exhibited similar response. Glutamate oxaloacetate transaminase (aspartate aminotransferase) and malate dehydrogenase, the functional enzymes of malate-aspartate shuttle, were decreased in soluble fraction of cerebral hemispheres and increased significantly in cerebellum after 16 hours of drug administration. Glutamate pyruvate transaminase (alanine aminotransferase) also showed an increase in the activity in cerebellum and brain stem after 8 hours of drug treatment. The EEG patterns obtained from 6-AN treated animals showed periodic bursts, turning to convulsive polyspike activity between 8-16 hours, indicating the onset of comatose-like stage. The results indicate that glutamate metabolism offers considerable anaplerotic potentials following impaired energy state after 6-AN treatment.
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PMID:6-Aminonicotinamide: EEG changes and effects on the activities of enzymes related to glutamate metabolism in rat brain regions. 287 43

The activities of alanine and aspartate transaminases, adenylate deaminase, glutamine synthetase and glutamate and xanthine dehydrogenases have been measured in liver, yolk sac membrane, intestine and breast and leg muscle of domestic fowl hatchlings receiving for 3 or 5 days either a standard diet or hard boiled eggwhite as well as in 3 or 5 days starved animals. The patterns of activation of amino acid metabolism enzymes were fully comparable in protein-fed and starved groups with respect to fed controls; the differences with respect to the latter became more marked in 5- than in 3-days old chicks. In 5-days old chicks intestine alanine transaminase activity increased in parallel to that of liver in protein-fed animals but not in those starved, in agreement with an enhanced alanine transfer between both organs under this situation. Both, starvation and protein-feeding, induced a general decrease in the amino acid metabolizing ability of muscle. Glutamine (but not alanine) synthetizing capabilities were enhanced.
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PMID:Effect of starvation and a protein diet on the amino acid metabolism enzyme activities of the organs of domestic fowl hatchlings. 287 42


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