Glucose Transport in Human Red Blood Cells

Abstract

The penetration of D-[ 14 C] glucose into human red blood cells (RBCs) features kinetic parameters which are readily distinguishable from passive permeation. It would be expected to require activation energy above 80 kJ/mol for permeation of glucose with five hydroxyls capable of forming hydrogen bonds, but the measured activation energy is approximately 16 kJ/mol. As a consequence, glucose permeates RBC membrane about five orders of magnitude faster than would be expected for passive permeation. Glucose transporter protein 1, or GLUT1 and SGLT1, present in all human tissues, but especially in RBCs. It is also anchored in the protective sheet of flat cells that line up the blood vessels of the brain. GLUT1 has a strong affinity for glucose and it ensures that both RBCs and the brain receive appropriate levels of glucose that they need to be able to function. The brain consumes ~120g of glucose per day; the blood glucose level in a typical person 80mg/100ml. The binding site of glucose faces intracellular and extracellular of the membrane alternately when it is loaded by a glucose. The transport is accomplished by conformational changes within GLUT1 , and not by rotation of the whole single long polypeptide chain (55kD, ~500 residues) with the presence of 12 trans membrane αhelices segments. The super family of related GLUT sugar transporters comprises 14 identified isoforms in the human genome, all adopting a 12-membrane-spanning domain structure that delineate 6 extracellular loops .The erythrocyte glucose transporter GLUT1 has an ~10-fold-lower affinity for D-glucose, K m ≈ 10-15 mM, at the inside face for net export than on the outside (K m = 1-2 mM) for net import of glucose (zero-trans net flux) at 24°C , pertaining a liganded consequential asymmetric transporter.

Effect of pregnancy and stage of lactation on energy processes in isolated blood cells of dairy cows

“…It was shown that 2–3 µmol/mL of lactate is formed in cows’ RBC per hour ( 13 ). Glucose transmembrane transport is an insulin-independent mechanism of facilitated diffusion through glucose transporters (GLUT-1) ( 10 ). Although glucose transport is insulin-independent we observed a moderate negative correlation of RBC glucose transmembrane transport with plasma insulin concentration ( Fig.…”

Dietary Energy Partition: The Central Role of Glucose

“…They require integer glucose, since they are not able to get energy via oxidation of 3C. Thus, these cells are considered purely glycolytic, releasing lactate from glucose [ 68 ]. Since the red blood cells need little energy and are a fundamental component of the blood (which carries glucose), their needs can be easily covered by direct uptake from plasma [ 69 ].…”

A Kinetic Model for Glucose Levels and Hemoglobin A1c Provides a Novel Tool for Individualized Diabetes Management

“…While this method improved the relationship between weighted average glucose and HbA1c, it has the limitation of assuming a fixed glycation rate 16,17 and failing to acknowledge variation in RBC cross-membrane glucose transport. 18,19 The use of kinetic modeling has been demonstrated by an empirical model, 20 which shows the association of recent glucose levels and HbA1c change; however, this model does not provide insight into the underlying mechanism affecting the glucose–HbA1c relationship. Understanding this mechanism is critical given the important role of HbA1c in diabetes management.…”