Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.1.1 (hexokinase)
 5,274 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. The effect of dexamethasone (30 micrograms day-1 100 g-1 body wt.) on the metabolism of glucose and glutamine was studied in the small intestine of rats after 9 days of treatment. 2. Dexamethasone treatment resulted in negative nitrogen balance (P less than 0.001), and produced increases in the concentrations of plasma glucose (22%, P less than 0.05), alanine (32%, P less than 0.001) and insulin (127%, P less than 0.001), but a decrease in the plasma concentration of glutamine (20%, P less than 0.05). 3. Portal-drained visceral blood flow increased by approximately 22% (P less than 0.001) in dexamethasone-treated rats, and was accompanied by a decrease in the arterio-venous concentration difference of glucose (43%, P less than 0.001) and an increase in that of lactate (22%, P less than 0.05), glutamine (35%, P less than 0.01), glutamate (33%, P less than 0.01) and alanine (21%, P less than 0.05). 4. Enterocytes isolated from dexamethasone-treated rats showed decreased and increased rates of glucose and glutamine utilization, respectively. 5. The maximal activities of hexokinase, 6-phosphofructokinase, citrate synthase and oxoglutarate dehydrogenase were decreased (30-64%, P less than 0.001) in intestinal mucosal scrapings of dexamethasone-treated rats, whereas the activity of glutaminase was increased (35%, P less than 0.001). 6. It is concluded that glucocorticoid administration decreases the rate of glucose utilization but increases that of glutamine (both in vivo and in vitro) by the epithelial cells of the small intestine. This may be caused by changes in the maximal activities of key enzymes in the pathways of glucose and glutamine metabolism in these cells.
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PMID:Effect of glucocorticoid treatment on glucose and glutamine metabolism by the small intestine of the rat. 340 28

1. The effects of burn injury (33 per cent of body surface area) on the activities of key enzymes in the metabolism of glucose, glutamine and ketone bodies in the epithelial cells of the small intestine and the rates of utilization of glucose, glutamine and ketone bodies by isolated enterocytes have been investigated. 2. Burn injury decreased the maximal activities of hexokinase and 6-phosphofructokinase and increased those of glucose 6-phosphatase plus fructose bisphosphatase (in duodenum, jejunum and ileum) over the first 5 days post-injury. 3. After injury there are decreases in the rates of glucose utilization and lactate formation by incubated enterocytes. 4. The maximal activities of citrate synthase and oxoglutarate dehydrogenase were increased during the first 5 days post-injury, whereas the ketone-body-utilizing enzymes were unchanged. 5. An increase in the maximal activity of phosphate-dependent glutaminase was observed during the whole of the post-injury period studied (20 days). 6. After burn injury there is an increased rate of glutamine utilization and increased rates of formation of glutamate and alanine by incubated enterocytes.
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PMID:Maximal activities of glutaminase and some enzymes of glycolysis and ketone body utilization and rates of utilization of glutamine, glucose and ketone bodies by intestinal mucosa after burn injury. 344 21

Laser irradiation of rats increases the activity of hexokinase and aerobic isoenzymes of lactate dehydrogenase, activates succinate- and alpha-oxoglutarate dehydrogenase and decreases the level of amino acids of a glutamine group.
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PMID:[Changes in carbohydrate-energy metabolism in the rat brain during laser irradiation]. 370 18

Maximum activities of some key enzymes of metabolism were studied in elicited (inflammatory) macrophages of the mouse and lymph-node lymphocytes of the rat. The activity of hexokinase in the macrophage is very high, as high as that in any other major tissue of the body, and higher than that of phosphorylase or 6-phosphofructokinase, suggesting that glucose is a more important fuel than glycogen and that the pentose phosphate pathway is also important in these cells. The latter suggestion is supported by the high activities of both glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase. However, the rate of glucose utilization by 'resting' macrophages incubated in vitro is less than the 10% of the activity of 6-phosphofructokinase: this suggests that the rate of glycolysis is increased dramatically during phagocytosis or increased secretory activity. The macrophages possess higher activities of citrate synthase and oxoglutarate dehydrogenase than do lymphocytes, suggesting that the tricarboxylic acid cycle may be important in energy generation in these cells. The activity of 3-oxoacid CoA-transferase is higher in the macrophage, but that of 3-hydroxybutyrate dehydrogenase is very much lower than those in the lymphocytes. The activity of carnitine palmitoyltransferase is higher in macrophages, suggesting that fatty acids as well as acetoacetate could provide acetyl-CoA as substrate for the tricarboxylic acid cycle. No detectable rate of acetoacetate or 3-hydroxybutyrate utilization was observed during incubation of resting macrophages, but that of oleate was 1.0 nmol/h per mg of protein or about 2.2% of the activity of palmitoyltransferase. The activity of glutaminase is about 4-fold higher in macrophages than in lymphocytes, which suggests that the rate of glutamine utilization could be very high. The rate of utilization of glutamine by resting incubated macrophages was similar to that reported for rat lymphocytes, but was considerably lower than the activity of glutaminase.
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PMID:Metabolism of glucose, glutamine, long-chain fatty acids and ketone bodies by murine macrophages. 380 Sep 71

Some enzyme activities and metabolic features of the black Ma melanotic, brown MI melanotic and Ab amelanotic melanomas of hamster were investigated. The activities of hexokinase and phosphofructokinase were similar in all three melanomas, the activity of NAD-dependent glycerol-3-phosphate dehydrogenase was higher in the amelanotic melanoma and that of pyruvate kinase and lactate dehydrogenase were slightly lower in MI than in the other tumors. The activities of citrate synthase, succinate dehydrogenase and malate dehydrogenase were higher in the Ma and MI melanotic melanomas than in the Ab amelanotic melanoma. The rate of labeled CO2 production from 6-14C-glucose, 1,5-14C-citric acid and U-14C-glutamine was about 2 times higher in melanotic melanomas than in amelanotic one, while no significant differences among the three melanomas were found in respect to 1-14C-glucose and U-14C-glycerol-3-phosphate. The production of 14CO2 was much higher from 1-14C-glucose than from 6-14C-glucose in all the melanomas studied. L-DOPA stimulated the production of 14CO2 from 1-14C-glucose much stronger in the Ma and MI melanomas than in the Ab melanoma. In none of the tumors the incorporation from 6-14C-glucose to CO2 was affected by L-DOPA. It is postulated that oxidation of glucose via the pentose phosphate cycle is involved in melanogenesis.
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PMID:Metabolic characterization of three hamster melanoma variants. 406 92

In incubated colonocytes isolated from rat colons, the rates of utilization O2, glucose or glutamine were linear with respect to time for over 30 min, and the concentrations of adenine nucleotides plus the ATP/ADP or ATP/AMP concentration ratios remained approximately constant for 30 min. Glutamine, n-butyrate or ketone bodies were the only substrates that caused increases in O2 consumption by isolated incubated colonocytes. The maximum activity of hexokinase in colonic mucosa is similar to that of 6-phosphofructokinase. Starvation of the donor animal decreased the activities of hexokinase and 6-phosphofructokinase, whereas it increased those of glucose-6-phosphatase and fructose-bisphosphatase. Isolated incubated colonocytes utilized glucose at about 6.8 mumol/min per g dry wt., with lactate accounting for 83% of glucose removed. These rates were not affected by the addition of glutamine, acetoacetate or n-butyrate, and starvation of the donor animal. Isolated incubated colonocytes utilized glutamine at about 5.5 mumol/min per g dry wt., which is about 21% of the maximum activity of glutaminase. The major end-products of glutamine metabolism were glutamate, aspartate, alanine and ammonia. Starvation of the donor animal decreased the rate of glutamine utilization by colonocytes, which is accompanied by a decrease in glutamate formation and in the maximum activity of glutaminase. Isolated incubated colonocytes utilized acetoacetate at about 3.5 mumol/min per g dry wt. This rate was not markedly affected by addition of glucose or by starvation of the donor animal. When colonocytes were incubated with n-butyrate, both acetoacetate and 3-hydroxybutyrate were formed, with the latter accounting for only about 19% of total ketones produced.
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PMID:Fuel utilization in colonocytes of the rat. 407 34

A suspension of cortical tissue fragments prepared by collagenase digestion of renal cortex obtained from fed and chronically acidotic (NH4Cl) rats was separated into four bands on a Percoll density gradient. By microscopic examination, vital staining with trypan blue, and histologic staining technique (periodic acid-Schiff) the F4 band was shown to contain only (greater than 98%) proximal tubules, whereas the F1 band was significantly enriched (70%) with distal tubules contaminated by glomeruli and short segments of proximal tubules. Intra/extracellular ratios for PAH of 15 were measured in the F4 band and of 2 in F1 band. ATP was 1.4 and 2.8 mumol/g in the F4 and F1 bands, respectively, and was stable for at least 60 min. The proximal F4 band was shown to be gluconeogenic (L-glutamine or L-lactate 2.5 mM as substrate) and to adapt to metabolic acidosis. The distal F1 band was shown to be glycolytic (glucose 2.5 mM) with no changes with acid-base status. All fractions were shown to metabolize glutamine, but the metabolic fate of this amino acid was different in proximal and distal structures. A F4/F1 activity ratio for the proximal cytoplasmic phosphoenolpyruvate carboxykinase enzyme of 2.6 and 4.3 was observed in normal and acidotic rats, respectively. In contrast, a F4/F1 ratio of 0.13 and 0.22 was observed for the distal cytoplasmic hexokinase enzyme. This preparation, therefore, allows the metabolism of a homogeneous population of proximal tubular fragments to be studied and can be used to obtain information on enzyme location within the nephron.
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PMID:Isolation of a pure suspension of rat proximal tubules. 611 31

1. The maximum activity of hexokinase in lymphocytes is similar to that of 6-phosphofructokinase, but considerably greater than that of phosphorylase, suggesting that glucose rather than glycogen is the major carbohydrate fuel for these cells. Starvation increased slightly the activities of some of the glycolytic enzymes. A local immunological challenge in vivo (a graft-versus-host reaction) increased the activities of hexokinase, 6-phosphofructokinase, pyruvate kinase and lactate dehydrogenase, confirming the importance of the glycolytic pathway in cell division. 2. The activities of the ketone-body-utilizing enzymes were lower than those of hexokinase or 6-phosphofructokinase, unlike in muscle and brain, and were not affected by starvation. It is suggested that the ketone bodies will not provide a quantitatively important alternative fuel to glucose in lymphocytes. 3. Of the enzymes of the tricarboxylic acid cycle whose activities were measured, that of oxoglutarate dehydrogenase was the lowest, yet its activity (about 4.0mumol/min per g dry wt. at 37 degrees C) was considerably greater than the flux through the cycle (0.5mumol/min per g calculated from oxygen consumption by incubated lymphocytes). The activity was decreased by starvation, but that of citrate synthase was increased by the local immunological challenge in vivo. It is suggested that the rate of the cycle would increase towards the capacity indicated by oxoglutarate dehydrogenase in proliferating lymphocytes. 4. Enzymes possibly involved in the pathway of glutamine oxidation were measured in lymphocytes, which suggests that an aminotransferase reaction(s) (probably aspartate aminotransferase) is important in the conversion of glutamate into oxoglutarate rather than glutamate dehydrogenase, and that the maximum activity of glutaminase is markedly in excess of the rate of glutamine utilization by incubated lymphocytes. The activity of glutaminase is increased by both starvation and the local immunological challenge in vivo. This last finding suggests that metabolism of glutamine via glutaminase is important in proliferating lymphocytes.
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PMID:Maximum activities of some enzymes of glycolysis, the tricarboxylic acid cycle and ketone-body and glutamine utilization pathways in lymphocytes of the rat. 716 29

An isolated rat brain preparation was perfused using glucose-free (= aglycemic) media. The high-energy phosphates, substrates of the glycolytic pathway, free amino acids, acetylcholine as well as the intracellular distribution of hexokinase activity were determined in brain tissues. The EEG was evaluated visually. The levels of glycolytic substrates, glutamate, and glutamine in cortical tissue decreased after aglycemic perfusion whereas the asparte level increased and the GABA level remained unchanged. The high-energy phosphate content seemed to be unaffected for about 15 min of aglycemic perfusion and fell significantly after 20 min. The EEG of the isolated brain changed rapidly after starting aglycemic perfusion and became isoelectric after 12--15 min. Hyperglycemic perfusion (35 mmol glucose per liter perfusion medium) did not alter the energy metabolism of the isolated brain. The breakdown of cerebral energy metabolism and of EEG activity was postponed when thiopental was added to the perfusion medium. The soluble hexokinase activity measured in cortical tissue was reduced after aglycemic perfusion and was enhanced after thiopental. Hyperglycemic perfusion did not influence the intracellular hexokinase distribution. The acetylcholine level in the striatum of the isolated rat brain was significantly decreased by aglycemia and was increased in hypothalamus by thiopental. It was suggested that hexokinase bound to the mitochondrial membrane may play an important role in the relationship of energy metabolism and neuronal activity.
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PMID:Studies on the linkage of energy metabolism and neuronal activity in the isolated perfused rat brain. 745 62

The effect of thyroid hormones on monocyte migration, phagocytic capacity and hydrogen peroxide production by macrophages and the effect of these hormones on glutamine and glucose metabolism was investigated. The experiments were performed on resident, thioglycollate- and BCG-stimulated cells from hypo- and hyperthyroid rats. High plasma levels of thyroid hormones suppressed the migration of monocytes and hydrogen peroxide production, whereas hypothyroidism did not affect cell migration but raised the phagocytic capacity and the hydrogen peroxide production. Hyperthyroidism increased the activities of glutaminase and hexokinase and the rates of decarboxylation of [U-14C]-glutamine and [U-14C]-glucose in inflammatory and activated cells. Hypothyroidism stimulated glucose metabolism and had only a slight effect on glutaminolysis. The activity of the TCA cycle was, however, diminished in the presence of high plasma levels of thyroid hormones and enhanced by the hypothyroid state. These findings suggest that the functional changes are more likely to be related to the activity of the TCA cycle rather than to glutaminolysis and glycolysis.
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PMID:Effect of hypo- and hyperthyroidism on the function and metabolism of macrophages in rats. 775 49


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