• Toxicological Research
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• v.11 no.2
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• pp.199-203
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• 1995

The focus of this study was to investigate that cellular parameters and glucose uptake might be altered by extracellular calcium and starvation. Addition of 1 mM $Ca^{++}$ to hepatocytes (equalling to the free calcium concentration of blood) significantly increased intracellular $Na^+$ and decreased $Na^+$ & LDH leakage. This pertains to the hepatocytes of control rats as well as those of rats fasted for 24 and 48. hr. These effects might be come from the membrane-stabilizing effects of calcium. But calcium had no effects on cell volumes, superoxide-formation and glucose uptake. Actually hepatocytes of starved rats showed changes in several cellular parameters. Starvation increased LDH leakage, glucose uptake and the total concentration of $Na^+$ and $Na^+$ whereas it markedly decreased cell volumes. Since total tonicity remained unchanged, intracellular $Na^+$ and $Na^+$ could contribute to a higher share of total osmolarity in starvation. Starvation increased the cytoplasmic pH because $R-NH^{3+}$ions and their corresponding counterions disappeared. This increase may be related to suppress the protonization of amino groups in proteins. Starvation decreased hepatic glycogen, a major compound that affects cytosolic volume of hepatocytes. The data indicate that starvation increases the glucose transport activity. The possible molecular basis will be discussed.

• The Korean Journal of Nuclear Medicine
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• v.36 no.2
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• pp.110-120
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• 2002

To clarify the difference in glucose uptake between human cancer cells and monocytes, we studied $[^{18}F]$ fluorodeoxyglucose (FDG) uptake in three human colon cancer cell lines (SNU-C2A, SNU-C4, SNU-C5), one human lung cancer cell line (NCI-H522), and human peripheral blood monocytes. The FDG uptake of both cancer cells and monocytes was increased in glucose-free medium, but decreased in the medium containing 16.7 mM glucose (hyperglycemic). The level of Glut1 mRNA decreased in human colon cancer cells and NCI-H522 under hyperglycemic condition. Glut1 protein expression was also decreased in the four human cancer cell lines under hyperglycemic condition, whereas it was consistently undetectable in monocytes. SNU-C2A, SNU-C4 and NCI-H522 showed a similar level of hexokinase activity (7.5 - 10.8 mU/mg), while SNU-C5 and monocytes showed lower range of hexokinase activity (4.3 - 6.5 mU/mg). These data suggest that glucose uptake is regulated by different mechanisms in human cancer cells and monocytes.

• Microbiology and Biotechnology Letters
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• v.24 no.4
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• pp.485-492
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• 1996

myo-Inositol, a growth factor for Saccharomyces cerevisiae (S. cerevisiae), has been known to be incorporated into phosphatidylinositol (PI), which is a kind of phospholipid in the cell membrane, by a membrane-associated PI-synthesizing enzyme. The deficiency of myo-inositol in S. cerevisiae adversely affected the membrane structure and function. On the basis of biochemical functions of myo-inositol, the effect of deficiency of myo-inositol on the aerobic glucose metabolism was investigated by measuring specific oxygen uptake rate (Q$_{O2}$) used as an indicator representing the respiratory capacity of S. cerevisiae in batch and continuous cultures. The respiratory capacity of aerobic glucose metabolism in S. cerevisiae was also monitored after glucose pulse-addition in a continuous culture (D=0.2, 1/hr), in which glucose was utilized through respiratory metabolism. The deficiency of myo-inositol was found to lead to both the decrease of the maximum specific oxygen uptake rate (Q$_{O2max}$) observed from the batch as well as in the continuous culture experiment and the decrease of the respiratory capacity of aerobic glucose metabolism of S. cerevisiae determined from the glucose pulse-addition experiment, in which the glucose flux into respiratory and fermen- tative metabolism was quantitatively analyzed.

• Journal of Pharmaceutical Investigation
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• v.24 no.3
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• pp.11-18
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• 1994

We have studied the iron uptake by the purified brush-border membrane vesicles (BBMVs) to determine the effect of fructose on the absorption of iron. BBMVs were prepared by the modified calcium precipitation method, The degree of purification was routinely assessed by the marker enzyme, alkaline phosphatase, and the functional integrity was tested by $D-[1-^3H]glucose$ uptake. The appearance of membrane vesicles was shown by transmission electron microscopy (TEM). The uptakes of complexes of labeled iron $[^{59}Fe]$ with fructose and ascorbate were measured with a rapid filtration technique, The uptake rate and pattern of the two iron-complexes, Fe(III)-fructose and Fe(III)-ascorbate, were also observed. A typical overshooting uptake of D-glucose was observed with peak value of $2{\sim}3$ times higher concentration than that at equilibrium. This result was similar to other studies with BBMVs. TEM showed that the size of BBMVs was uniform and we can hardly find any contaminants, Fe(III)-fructose has the higher value of $V_{max}$ and the lower value of Km than those of Fe(III)-ascorbate, respectively. It may be concluded that D-fructose is more effective in promoting the iron absorption than ascorbate.

• Current Research on Agriculture and Life Sciences
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• v.24
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• pp.29-35
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• 2006

In this study we evaluated the anti-diabetic potential of Puerariae Radix and its isoflavone (puerarin) by investigating their inhibitory activities against digestive enzymes, ${\alpha}$-amylase, ${\alpha}$-glucosidase and lipase and effect on glucose uptake and PPAR ${\gamma}$ expression. The activities of carbohydrate digestive enzymes were not inhibited by puerarin. Glucose uptake in differentiated adipocytes was stimulated by puerarin. Furthermore, puerarin enhanced the differentiation of preadipocytes as evaluated by triacylglycerol (TG) accumulation, which is specific for differentiated adipocytes. The effect of puerarin on expression of peroxisome proliferator-activated receptor ${\gamma}$ (PPAR-${\gamma}$) gene, which is associated with obesity and dyslipidemia, was examined by both real-time PCR and reverse transcriptase PCR. The study demonstrated that puerarin increased the expression of PPAR-${\gamma}$. In conclusion, puerarin showed potential to exert anti-diabetic action by enhancing cellular glucose uptake and thereby TG accumulation in adipocyte tissue.

• YAKHAK HOEJI
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• v.40 no.6
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• pp.734-738
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• 1996

The development of the alpha2 isoform of (Na,K)ATPase which is high affinity ouabain receptors was studied in the differentiating nonfusing muscle cell line BC3H-1. T he differentiation process of BC3H-1 cell line was confirmed by 2-dexy-D-[$^3$H] glucose uptake experiment and the quantity of the expression of ${\alpha}_2$ isoform was measured using a whole cell [$^3$H] ouabain-binding assay. Undifferentiated growing BC3H-1 cells, myoblasts, exhibited low levels of insulin-stimulated glucose uptake and [$^3$H] ouabain-binding sites. In contrast, differentiated BC3H-1 cells, myocytes, had a 5.6-fold increase in insulin-stimulated glucose uptake and 5-fold increase in [$^3$H] ouabain-binding sites. Scatchard analysis showed that myocytes developed more [$^3$H] ouabain-binding sites than myoblasts vath a dissociation constant (kd) of 6${\times}10^{-8}$M and capacity of 6.l${\times}10^{-5}$ sites/cell. Therefore. it seems that myoblasts express low levels of ${\alpha}_2$ subunit and probably the majority of ${\alpha}_1$ subunit, whereas myocytes express high levels of ${\alpha}_2$ isoform. The results indicate that the expression of ${\alpha}_2$ isoform is developmentally regulated during differentiation and that BC3H-1 culture system provides an excellent model for the study of differentiation and mechanism of (Na,K)ATPase action in muscle which requires electrical excitability.

• Journal of the Korean Society of Food Science and Nutrition
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• v.46 no.1
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• pp.39-45
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• 2017

This study investigated the glycyrrhizic acid content and anti-diabetic activities of Glycyrrhiza uralensis (GU) depending on the cultivation region (Jecheon, Youngju, Gokseong, China, and Uzbekistan). Glycyrrhizic acid accuracy recovery and intra- and inter-day precisions (RSD%) of the method were calculated at 99.10~107.07% and 3.92 and 6.31% for GU samples, respectively, whereas the limits of detection and quantitation were 0.14 and $0.20{\mu}g/mL$. Anti-diabetic activity was measured by ${\alpha}-glucosidase$ and glucose uptake. GU (20 g) was extracted with 70% ethanol at $70^{\circ}C$ for 6 h. The Jecheon and Gokseong GU showed good inhibitory activity compared to the control. The Jecheon, Youngju, and Uzbekistan GU ethanol extracts ($100{\mu}g/mL$) showed glucose uptakes (in $C_2C_{12}$ myotube) of 124.19, 127.18, and 126.92%, respectively, compared to the positive control. In conclusion, these methods were validated for detection of glycyrrhizic acid in GU, and the results indicate that GU might have potential anti-diabetic activities.

• BMB Reports
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• v.38 no.4
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• pp.468-473
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• 2005

The energetics of nitrate uptake by intact cells of the halotolerant cyanobacterium Aphanothece halophytica were investigated. Nitrate uptake was inhibited by various protonophores suggesting the coupling of nitrate uptake to the proton motive force. An artificially-generated pH gradient across the membrane (${\Delta}pH$) caused an increase of nitrate uptake. In contrast, the suppression of ${\Delta}pH$ resulted in a decrease of nitrate uptake. The increase of external pH also resulted in an enhancement of nitrate uptake. The generation of the electrical potential across the membrane ($\Delta\psi$) resulted in no elevation of the rate of nitrate uptake. On the other hand, the valinomycin-mediated dissipation of $\Delta\psi$ caused no depression of the rate of nitrate uptake. Thus, it is unlikely that $\Delta\psi$ participated in the energization of the uptake of nitrate. However, $Na^+$-gradient across the membrane was suggested to play a role in nitrate uptake since monensin which collapses $Na^+$-gradient strongly inhibited nitrate uptake. Exogenously added glucose and lactate stimulated nitrate uptake in the starved cells. N, N'-dicyclohexylcarbodiimide, an inhibitor of ATPase, could also inhibit nitrate uptake suggesting that ATP hydrolysis was required for nitrate uptake. All these results indicate that nitrate uptake in A. halophytica is ATP-dependent, driven by ${\Delta}pH$ and $Na^+$-gradient.

• The Korean Journal of Zoology
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• v.11 no.3
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• pp.75-82
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• 1968

The effects of x-irradiation on the utilization of glucose, succinate, citrate and $\\alpha$-ketoglutarate, on the response of the cell metabolism to $NaN_3$ and DNP, and on the uptake of lysine in the presence or absence of the metabolitesor the inhibitors were studied using HeLa cells and the results are summarized as follows: 1. 200r of x-irradiation had no immediate effect on the oxygen consumption of cells. 2. The oxygen consumption was greatly stimulated by succinate, $\\alpha$-ketoglutarate and citraed and in decreasing order and x-irradiation caused no remarkable change in this order. 3. The respiratory response of the cell to the metabolic inhibitors seems to be altered by x-irradiation. 4. The initial rate of the uptake of lysine was markedly retarded and the accumulation of lysine in the cell was decreased by irradiation. 5. Glucose increased the lysine uptake whereas succinate had no effect and citrate and $\\alpha$-ketoglutarate reduced the absorption. X-irradiation did not alter this tendency. 6. The inhibitory effects of $NaN_3$ and DNP on the lysine uptake were quite different from those seen in the oxygen consumption.

• Biomedical Science Letters
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• v.11 no.4
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• pp.487-492
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• 2005

The baculovirus/insect cell expression system is of great value in the study of structure-function relationships in mammalian glucose-transport proteins by site-directed mutagenesis and for the large-scale production of these proteins for mechanistic and biochemical studies. Spodoptera frugiperda Clone 21 (Sf2l) 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, very little is known about the properties of the endogenous sugar transporter(s) in Sf2l cells, although a saturable transport system for hexose uptake has been previously revealed in the Sf cells. In order to further examine the substrate and inhibitor recognition properties of the Sf2l cell transporter, the ability of hexoses to inhibit 2-deoxy-D-glucose (2dGlc) transport was investigated by measuring inhibition constants $(K_i)$. The $K_i's$ for reversible inhibitors were determined from plots of uptake versus inhibitor concentration. Transport was effectively inhibited by D-mannose and D-glucose. Of the hexoses tested, L-glucose had the least effect on 2dGlc transport in the Sf2l cells, indicating that the transport is stereoselective. Unlike the human HepG2 type glucose transport system, D-mannose had a somewhat greater affinity for the Sf2l cell transporter than D-glucose, implying that the hydroxyl group at the C-2 position is not necessary for strong binding. However, epimerization at the C-4 position of D-glucose (D-galactose) resulted in a dramatic decrease in affinity of the hexose for the Sf2l cell transporter. Such a lowering of affinity might be the result of the involvement of the C-4 hydroxyl in hydrogen bonding. It is therefore suggested that Sf2l cells were found to contain an endogenous sugar transport activity that in several aspects resembles the human HepG2 type glucose transporter, although the insect and human transporters do differ in their affinity for cytochalasin B.