Decreased Na+-gradient-dependent d-glucose transport in brush-border membrane vesicles from rabbits with experimental fanconi syndrome

1983 ◽  
Vol 733 (1) ◽  
pp. 95-101 ◽  
Author(s):  
Masahiro Yanase ◽  
Yoshimasa Orita ◽  
Noriyuki Okada ◽  
Takeshi Nakanishi ◽  
Masaru Horio ◽  
...  
Keyword(s):  
Glucose Transport ◽  
Brush Border ◽  
Fanconi Syndrome ◽  
Brush Border Membrane ◽  
Membrane Vesicles ◽  
Brush Border Membrane Vesicles

D-glucose uptake is increased in jejunal brush-border membrane vesicles from hyperthyroid chicks

1989 ◽  
Vol 120 (4) ◽  
pp. 435-441 ◽  
Author(s):  
Hanna Debiec ◽  
Heide S. Cross ◽  
Meinrad Peterlik
Keyword(s):  
Glucose Uptake ◽  
Glucose Transport ◽  
Brush Border ◽  
Transmembrane Potential ◽  
Brush Border Membrane ◽  
Membrane Vesicles ◽  
Brush Border Membrane Vesicles ◽  
Potential Difference ◽  
Daily Injection ◽  
Transmembrane Potential Difference

Abstract. Jejunal brush-border membrane vesicles were harvested from 4-week old chicks whose thyroid status had been altered either by a daily injection of 20 μg T3 for 1 week or which through the preceding 4 weeks had received propylthiouracil and than had been repleted with either 20 or 80 μg T3 in divided doses within 48 h. T3 markedly stimulated D-glucose uptake in brush-border membrane vesicles in the presence of an outside/inside (100/0 mmol/l) Na+ gradient. T3 administration had no detectable influence on the Na+ permeability of the isolated vesicles. The effect of the thyroid hormone on Na+ gradient-driven D-glucose uptake was fully preserved at zero transmembrane potential difference. These findings exclude that T3 stimulates Na+-dependent D-glucose transport in the small intestine through changes of the electrochemical Na+ gradient or through alteration of the transmembrane potential difference. Tracer exchange experiments under equilibrium and voltageclamp conditions revealed a significantly shorter halftime of D-glucose uptake in brush-border membrane vesicles from T3-treated chicks. Kinetic analysis showed that T3 administration significantly increases the apparent maximal velocity of D-glucose transport in brushborder membrane vesicles, whereas the apparent Km values were virtually unaltered. From these data we conclude that T3 increases the activity of Na+-dependent D-glucose carriers in the brush-border membrane. This is interpreted as consistent with a greater rate of D-glucose absorption from the intestinal lumen under conditions of hyperthyroidism.

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