• Asian-Australasian Journal of Animal Sciences
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• v.15 no.8
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• pp.1210-1214
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• 2002

The large and rapid changes of glucose utilization in lactating mammary tissue in response to changes in nutritional state must be largely related by external signal of insulin. This also must be related with the quantity and composition of the diet in vivo. To characterize the mode of gut extract protein with insulin, in vitro experiment was conducted with HC11 cells. The gut extract protein has not only the same effect as insulin alone but also the synergistic effect with insulin in 2-Deoxy[3H] glucose uptake. Although the gut extract did not modulates glucose uptake via increasing the rate of translation of the GLUT1 protein, northern blot analysis indicated that the gut extract protein increased the expression of GLUT1 mRNA by a threefold and also there was a dose-dependent increase in the expression of GLUT1 mRNA. The gut extract protein is therefore shown to be capable of modulating glucose uptake by transcription level with insulin in HC 11 cells.

• Biomedical Science Letters
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• v.11 no.3
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• pp.327-332
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• 2005

Sf21 cells become popular as the host permissive cell line to support the baculovirus AcNPV replication and protein synthesis. The cells grow well on TC-100 medium that contains $0.1\%$ D-glucose as the major carbon source, strongly suggesting the presence of endogenous glucose transporters. However, unlike human glucose transporters, very little is known about the characteristics of the endogenoussugar transporter(s) in Sf21 cells. Thus, some kinetic properties of the sugar transport system were investigated, involving the uptake of 2-deoxy-D-glucose (2dG1c). In order to obtain a true measure of the initial rate of uptake, the uptake of $[^3H]2dGlc$ from both low $(100{\mu}M)$ and high (10 mM) extracellular concentrations was measured over periods ranging from 30 sec to30 min. The data obtained indicated that the uptake was linear for at least 2 min at both concentrations, suggesting that measurements made over a 1min time course would reflect initial rates of the jexpse uptake. To determine $K_m\;and\;V_{max}$ of the endogenous glucose transporter(s) in Sf21 cells, the uptake of 2dG1c was measured over a range of substrate concentrations $(50{\mu}M\~10mM)$ 2dG1c uptake by the Sf21 cells appeared to involve both saturable and non-saturable (or very low affinity) components. A saturable transport system for 2dG1c was relatively high, the $K_m$ value for uptake being < 0.45 mM. The $V_{max}$ value obtained for 2dG1c transport in the Sf21 cells was about 9.7-folds higher than that reported for Chinese hamster ovary cells, which contain a GLUT1 homologue. Thus, it appeared that the transport activity of the Sf21 cells was very high. In addition, the Sf21 glucose transporter was found to have very low affinity for cytochalasin B, a potent inhibitor of human erythrocyte glucose transporter

• Food Science and Biotechnology
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• v.17 no.2
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• pp.274-278
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• 2008

Ethanol extracts from the edible mushroom hinmogi (Tremella fuciformis, TF) were used in the investigation of effects on $\alpha$-glucosidase in vitro and on glucose-uptake in 3T3-L1 mature adipocytes. Addition of the extract significantly inhibited $\alpha$-glucosidase from small intestine of porcine and of rat (about 42 and 35% of control, respectively), and stimulated glucose uptake (about 100% of control), of which activity was higher than that of maitake (Grifola frondosa) X-fraction, a well known anti-diabetic substance. When the ethanol extracts were further partitioned successively by organic solvents and purified by silica gel chromatography, the non-polar layer (F-7) from hexane layer showed highest stimulatory activity of glucose-uptake among layers tested. The major components of the F-7 were 1-monooleoylglycerol and 1-monopalmitoylglycerol. Our report is the first description of TF with stimulatory activity of glucose-uptake. These results suggest that TF extracts may constitute a new source of glucose transport activator and could be employed as a potential anti-diabetic material for treatment and preventing diabetes.

• The Journal of Internal Korean Medicine
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• v.41 no.4
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• pp.599-611
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• 2020

Objectives: The aim of this study was to evaluate the effects of Hwanggi-tang on glucose digestion, uptake, and metabolism in murine C2C12 myotubes. Methods: Hwanggi-tang was prepared according to the Dong-ui-bo-gam (≪東醫寶鑑≫) prescription by 70% ethanol extraction. The effect on glucose digestion was examined by determining the inhibitory effect of Hwanggi-tang on α-glucosidase activity. We also compared and verified the gene and protein expression of genes related to glucose uptake in C2C12 myotubes treated with Hwanggi-tang or insulin. Glucose metabolism was assessed by the expression levels of associated enzymes. Results: Hwanggi-tang caused a dose-dependent inhibition of α-glucosidase activity, induced glucose uptake by activation of the PI3K/Akt/mTOR pathway in the insulin signaling pathway, and promoted glucose oxidation and β-oxidation. Conclusions: Hwanggi-tang exerts an anti-diabetic effect on murine myotubes by inhibiting glucose digestion and inducing glucose uptake and consumption.

• Korean Journal of Pharmacognosy
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• v.36 no.4 s.143
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• pp.291-298
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• 2005

Anti-hyperglycemic effects of 17 medicinal plants that have been used for ameliorating diabetes in oriental medicine were evaluated using glucose transport assay in 3T3-L1 adipocytes. Higher activities were obtained by treating water or alcohol extract of Phellodendri Cortex (PC), which showed enhancing effects both on basal and insulin-stimulated glucose uptake. The latter effect of PC was completely inhibited by wortmannin, a specific inhibitor for phosphatidyl inositol 3-kinase (PI 3-kinase), but not affected by SB203580, A specific inhibitor for p38 mitogen-activatedprotein kinase(MAPK). Genistein, an inhibitor for tyrosine kinases, abolished the PC effects completely. Treatment of vanadate, an inhibitor for tyrosine phosphatases, together with PC showed no significant synergic enhancement in glucose uptake. The results of inhibitors associated with insulin signaling pathway indicated that extracts of PC enhance glucose uptake by PI-3 kinase activation which is an upstream event for GLUT4 translocation. Antidiabetic effects of PC extract might be also due to enhanced tyrosine phosphorylation and reduced tyrosine dephosphorylation. In addition, PC accelerated insulin-stimulated glucose uptake in insulin-resistant cells, recovering the uptake level close to that of normal cells. These findings may offer a new way to utilize extracts of PC as novel anti-hyperglycemic agents.

• The Korean Journal of Physiology
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• v.29 no.1
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• pp.69-80
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• 1995

Renal proximal tubular hypertrophy and hyperfunction are known to be early manifestations of experimental and human diabetes. As the hypertrophy and hyperfunction have been suggested to be central components in the progression to renal failure, an understanding of their underlying causes is potentially important for the development of therapy. A primary rabbit kidney proximal tubule cell culture system was utilized to evaluate the possibility that the renal proximal tubular hypertrophy and hyperfunction observed in vivo in diabetes mellitus, can be attributed to effects of elevated glucose levels on membrane transport systems. Primary cultures of rabbit proximal tubules, which achieved confluence at 10 days, exhibited brush-border characteristics typical of proximal tubular cells. Northern analysis indicated $2.2{\sim}2.3$ and 2.0 kb Na/glucose cotransporter RNA species appeared in fresh and cultured proximal tubule cells after confluence, repectively. The cultured cells showed reduced Na/glucose cotransporter activity compared to fresh proximal tubules. Primary cultured proximal tubule cells incubated in medium containing 20 mM glucose have reduced ${\alpha}-MG$ transport compared to cells grown in 5 mM glucose. In the proximal tubule cultures incubated in medium containing 5 mM or 20 mM glucose, phlorizin at 0.5 mM inhibited 0.5 mM ${\alpha}-MG$ uptake by 84.35% or 91.85%, respectively. The uptake of 0.5 mM ${\alpha}-MG$ was similarly inhibited by 0.1 mM ouabain (41.97% or 48.03% inhibition was observed, respectively). In addition, ${\alpha}-MG$ uptake was inhibited to a greater extent when $Na^{+}$ was omitted from the uptake buffer (81.86% or 86.73% inhibition was observed, respectively). In cell homogenates derived from the primary cells grown in 5 mM glucose medium, the specific activity of the Na/K-ATPase $(6.17{\pm}1.27\;{\mu}mole\;Pi/mg\;protein/hr)$ was 1.56 fold lower than the values in cell homogenates treated with 360 mg/dl D-glucose, 20 mM $(9.67{\pm}1.22\;{\mu}mole\;Pi/mg\;protein/hr)$. Total $Rb^{+}$ uptake occurred at a significantly higher rate (1.60 fold increase) in primary cultured rabbit kidney proximal tubule cell monolayers incubated in 20 mM glucose medium $(10.48{\pm}2.45\;nM/mg\;protein/min)$ as compared with parallel cultures in 5 mM glucose medium. $Rb^{+}$ uptake rate in 5 mM glucose medium was reduced by 28% when the cultures were incubated with 1 mM ouabain. The increase of the $Rb^{+}$ uptake by rabbit kidney proximal tubule cells in 20 mM glucose could be attributed primarily to an increase in the rate of ouabain-sensitive $Rb^{+}$ uptake $(5\;mM\;to\;20\;mM;\;4.68{\pm}0.85\;to\;8.38{\pm}1.37\;nM/mg\;protein/min)$. In conclusion, the activity of the renal proximal tubular Na,K-ATPase is elevated in high glucose concentration. In contrast, the activity of the Nafglucose cotransport system is inhibited.

• Korean Journal of Animal Reproduction
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• v.19 no.3
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• pp.161-169
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• 1995

To investigate the metabolism of various substrates in preimplantation bovine embryos, uptake of glucose and pyruvate, and lactate production were measured in single IVF-derived bovine embryos by a non-invasive method. When the embryos were incubated for 5 h in culture medium supplemented with 1 mM glucose and 0.4mM pyruvate as substrates at each developmental stage, glucose uptake was increased with more advanced developmental stages while pyruvate uptake was decreased. Total lactate producton of 2-cell embryos was significantly higher than that of blastocysts (p<0.05). Both of glucose uptake and lactate production in normal morulae produced in vitro was significantly high compared to the degenerated embryos(p<0.05). The results obtained in the study suggest that pyruvate as an exogenous substrate may be support in bovine embryos until 8-cell stage, whereas glucose may be effective as an energy source after morula stage. In addition, it was proven thatlactate was not effective as an energy source in preimplantation development of IVF-derived bovine embryos.

• The Korean Journal of Nuclear Medicine
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• v.33 no.1
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• pp.1-10
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• 1999

Cancer cells are known to show increased rates of glycolysis metabolism. Based on this, PET studies using F-18-fluorodeoxyglucose have been used for the detection of primary and metastatic tumors. To account for this increased glucose uptake, a variety of mechanisms has been proposed. Glucose influx across the cell membrane is mediated by a family of structurally related proteins known as glucose transporters (Gluts). Among 6 isoforms of Gluts, Glut-1 and/or Glut-3 have been reported to show increased expression in various tumors. Increased level of Glut mRNA transcription is supposed to be the basic mechanism of Glut overexpression at the protein level. Some oncogens such as src or ras intensely stimulate Glut-1 by means of increased Glut-1 mRNA levels. Hexokinase activity is another important factor in glucose uptake in cancer cells. Especially hexokinase type II is considered to be involved in glycolysis of cancer cells. Much of the hexokinase of tumor cells is bound to outer membrane of mitochondria by the porin, a hexokinase receptor. Through this interaction, hexokinase may gain preferred access to ATP synthesized via oxidative phosphorylation in the inner mitochondria compartment. Other biologic factors such as tumor blood flow, blood volume, hypoxia, and infiltrating cells in tumor tissue are involved. Relative hypoxia may activate the anaerobic glycotytic pathway. Surrounding macrophages and newly formed granulation tissue in tumor showed greater glucose uptake than did viable cancer cells. To expand the application of FDG PET in oncology, it is important for nuclear medicine physicians to understand the related mechanisms of glucose uptake in cancer tissue.

• Journal of Yeungnam Medical Science
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• v.7 no.1
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• pp.29-37
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• 1990

The effects of insulin and exercise on glucose uptake of skeletal muscle were investigated in soleus muscle isolated from low dose streptozotocin induced diabetic rats in vitro. Glucose uptake was assessed by measuring $^3H$-methylglucose uptake in vitro. Basal glucose uptake in diabetes was reduced by approximately one-third of the control value($5.6{\pm}0.73{\mu}Mol$/g/20min. in diabetes versus $8.4{\pm}0.77$ in control, P<0.01). There was also a significant decrease(P<0.01) in glucose uptake of diabetes at physiologic insulin concentration ($200{\mu}IU$/ml) by 40% ($6.1{\pm}1.20$ versus $10.0{\pm}0.81$). Furthermore, maximal insulin($20000{\mu}IU$/ml)-stimulated glucose uptake was 36% lower in diabetes as compared with control($7.3{\pm}1.29$ versus $11.4{\pm}1.29$, P<0.01). In contrast, exercise(1.0km/hr, treadmill running for 45min.) effect on glucose uptake was so dramatic in diabetes that glucose uptake at basal state was 8.4+1.09 and insulin stimulated-glucose uptake were $10.2{\pm}1.47$ and $11.9{\pm}1.64$, in 200 and $20000{\mu}IU$/ml added insulin, respectively. These results suggest that insulin insensitivity develops in skeletal muscle after 2 weeks of streptozotocin-induced diabetes, but these insensitivity was recovered significantly by single session of running exercise.

• Journal of Plant Biology
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• v.30 no.4
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• pp.277-285
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• 1987

Undifferentiated suspension cells had the ability to transfer glucose and fructose actively, but the suspension culture cells were unable to transfer saccharide without previously splitting to monosccarides. The uptake of fructose showed the low- and high-affinity system compared to of glucose, which possessed only one saturable uptake system. In this paper, the low affinity system of the uptake of fructose has been studied intensively. Glucose did not inhibit the low affinity system of fructose competitively. The Km value was 47 mM for fructose, 7.4 mM for glucose and Vmax was 69 $\mu$mol/h.g fresh weight for fuctose, 9.8 $\mu$ mol/h.g fresh weight for glucose. Metabolizer inhibitors, both 50 $\mu$M of CCCP and DNP, inhibited 70% of the uptake of the low affinity system of fructose. The proton ions were accompanied by the uptake of fructose. The stoichiometry showed ratio of proton to fructose was 0.17. The mechanism ofthe uptake was fructose-proton-symport. The molecules of fructose accmululated inside 25 times more than outside. Therefore, the low affinity system of fructose was not mere diffusion, but depended on metabolic energy and thus transported actively. The importance of this system was discussed.