scholarly journals In vitro analysis of the glucose-transport system in GLUT4-null skeletal muscle

1999 ◽  
Vol 342 (2) ◽  
pp. 321 ◽  
Author(s):  
Jeffrey W. RYDER ◽  
Yuichi KAWANO ◽  
Alexander V. CHIBALIN ◽  
Jorge RINCÓN ◽  
Tsu-Shuen TSAO ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Glucose Transport ◽  
Transport System ◽  
Glucose Transport System ◽  
Vitro Analysis ◽  
In Vitro Analysis

scholarly journals In vitro analysis of the glucose-transport system in GLUT4-null skeletal muscle

1999 ◽  
Vol 342 (2) ◽  
pp. 321-328 ◽  
Author(s):  
Jeffrey W. RYDER ◽  
Yuichi KAWANO ◽  
Alexander V. CHIBALIN ◽  
Jorge RINCÓN ◽  
Tsu-Shuen TSAO ◽  
...  
Keyword(s):  
Cell Surface ◽  
Glucose Transport ◽  
Transport System ◽  
Soleus Muscle ◽  
Cytochalasin B ◽  
Transport Activity ◽  
Wild Type ◽  
Glucose Transport System ◽  
Vitro Analysis

We have characterized the glucose-transport system in soleus muscle from female GLUT4-null mice to determine whether GLUT1, 3 or 5 account for insulin-stimulated glucose-transport activity. Insulin increased 2-deoxyglucose uptake 2.8- and 2.1-fold in soleus muscle from wild-type and GLUT4-null mice, respectively. Cytochalasin B, an inhibitor of GLUT1- and GLUT4-mediated glucose transport, inhibited insulin-stimulated 2-deoxyglucose uptake by > 95% in wild-type and GLUT4-null soleus muscle. Addition of 35 mM fructose to the incubation media was without effect on insulin-stimulated 3-O-methylglucose transport activity in soleus muscle from either genotype, whereas 35 mM glucose inhibited insulin-stimulated (20 nM) 3-O-methylglucose transport by 65% in wild-type and 99% in GLUT4-null mice. We utilized the 2-N-4-1-(1-azi-2,2,2-t r i f l u o r o e t h y l ) b e n z o y l - 1, 3 - b i s (D - m a n n o s e - 4 - y l o x y ) - 2 - p ro p y lamine (ATB-BMPA) exofacial photolabel to determine if increased cell-surface GLUT1 or GLUT4 content accounted for insulin-stimulated glucose transport in GLUT4-null muscle. In wild-type soleus muscle, cell-surface GLUT4 content was increased by 2.8-fold under insulin-stimulated conditions and this increase corresponded to the increase in 2-deoxyglucose uptake. No detectable cell-surface GLUT4 was observed in soleus muscle from female GLUT4-null mice under either basal or insulin-stimulated conditions. Basal cell-surface GLUT1 content was similar between wild-type and GLUT4-null mice, with no further increase noted in either genotype with insulin exposure. Neither GLUT3 nor GLUT5 appeared to account for insulin-stimulated glucose-transport activity in wild-type or GLUT4-null muscle. In conclusion, insulin-stimulated glucose-transport activity in female GLUT4-null soleus muscle is mediated by a facilitative transport process that is glucose- and cytochalasin B-inhibitable, but which is not labelled strongly by ATB-BMPA.

Substrate specificity of the high-affinity glucose transport system of Pseudomonas aeruginosa

1993 ◽  
Vol 39 (7) ◽  
pp. 722-725 ◽  
Author(s):  
John L. Wylie ◽  
Elizabeth A. Worobec
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Glucose Transport ◽  
Transport System ◽  
Binding Protein ◽  
High Affinity ◽  
Glucose Binding ◽  
Glucose Transport System ◽  
Glucose Binding Protein

Specificity of the high-affinity glucose transport system of Pseudomonas aeruginosa was examined. At a concentration of [14C]glucose near the Vmax of the system, inhibition by maltose, galactose, and xylose was detected. This inhibition is similar to that detected in earlier in vivo studies and correlates with the known specificity of OprB, a glucose-specific porin of P. aeruginosa. At a level of [14C]glucose 100 times lower, only unlabelled glucose inhibited uptake to any extent. This matches the known in vitro specificity of the periplasmic glucose binding protein. These findings were used to explain the discrepancy between earlier in vivo and in vitro results reported in the literature.Key words: Pseudomonas aeruginosa, glucose transport, OprB, glucose binding protein.

The effect of worm, age, weight and number in the infection on the absorption of glucose by Hymenolepis diminuta

Parasitology ◽  
1977 ◽  
Vol 75 (3) ◽  
pp. 277-284 ◽  
Author(s):  
D. Henderson
Keyword(s):  
Glucose Transport ◽  
Transport System ◽  
Weight Ratio ◽  
Dry Weight ◽  
Glucose Absorption ◽  
Hymenolepis Diminuta ◽  
Glucose Transport System ◽  
Rate Of Absorption ◽  
Single Worm

SummaryIn Hymenolepis diminuta the in vitro rate of absorption of glucose/unit dry weight of worm falls with increasing worm age, with increasing worm weight and as the number of worms in an infection is increased. In a 6 mM solution of glucose, a 5 mg (dry weight) worm from a 7 or 8 worm infection absorbed 80 µmoles/g dry weight/5 min whereas a 60 mg worm, also from a 7 or 8 worm infection, absorbed only 35µmoles/g dry weight/5 min. This change in the rate of absorption is, at least partly, thought to be due to changes in the relative surface area: weight ratio during growth of the worm.The kinetic parameter, Kt glucose, increased from 1.1 mM for a 5 mg (dry weight) worm from a 7 or 8 worm infection to 2 mM for a 60 mg worm. This change in the functioning of the glucose transport system may indicate that there are two components of the glucose transport system – or two separate systems – one with a low Kt and one with a high Kt, the ratios of which change during worm growth.The smaller the number of worms in an infection the greater the rate of glucose absorption. Using 8–day–old worms in a 6 mM glucose solution, 1 worm from a single worm infection absorbs 111 μmoles/g dry weight/5 min, 1 worm from a 7 or 8 worm infection absorbs 88 μmoles/g dry weight/5 min and 1 worm from a 45–50 worm infection absorbs 77 μmoles/g dry weight/5min. The significance of this is discussed with reference to the ‘crowding effect’ in tapeworms.

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