The role of GLUT1 in the sugar-induced dielectric response of human erythrocytes.
We propose a key role for the glucose transporter 1 (GLUT1) in mediating the observed changes in the dielectric properties of human erythrocyte membranes as determined by dielectric spectroscopy. Cytochalasin B, a GLUT1 transport inhibitor, abolished the membrane capacitance changes in glucose-exposed red cells. Surprisingly, D-fructose, known to be transported primarily by GLUT5, exerted similar membrane capacitance changes at increasing D-fructose concentrations. In order to evaluate whether the glucose-mediated membrane capacitance changes originated directly from intracellularly bound adenosine triphosphate (ATP) or other components of the glycolysis process, we studied the dielectric responses of swollen erythrocytes with a decreased ATP content and of nucleotide-filled ghosts. Resealed ghosts containing physiological concentrations of ATP yielded the same glucose-dependent capacitance changes as biconcave intact red blood cells, further supporting the finding that ATP is the effector of the glucose-mediated dielectric response where the ATP concentration is also the mediating factor in swollen red blood cells. The results suggest that ATP binding to GLUT1 elicits a membrane capacitance change that increases with the applied concentration gradient of D-glucose. A simplified model of the membrane capacitance alteration with glucose uptake is proposed.
Livshits
Leonid
L
Department of Applied Physics, The Hebrew University of Jerusalem, Givat Ram, Jerusalem 91904, Israel.
Caduff
Andreas
A
Talary
Mark S
MS
Lutz
Hans U
HU
Hayashi
Yoshihito
Y
Puzenko
Alexander
A
Shendrik
Andrey
A
Feldman
Yuri
Y
D000255:Adenosine Triphosphate / Q000737:chemistry / Q000378:metabolism; D002241:Carbohydrates / Q000737:chemistry* / Q000502:physiology; D003571:Cytochalasin B / Q000494:pharmacology; D004910:Erythrocyte Membrane / Q000378:metabolism; D004912:Erythrocytes / Q000737:chemistry / Q000378:metabolism*; D051272:Glucose Transporter Type 1 / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism*; D051296:Glucose Transporter Type 5 / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D008958:Models, Molecular; D012016:Reference Values; D013057:Spectrum Analysis
D002241:Carbohydrates; D051272:Glucose Transporter Type 1; D051296:Glucose Transporter Type 5; D003571:Cytochalasin B; D000255:Adenosine Triphosphate