Polyol permeability of the human red cell. Interpretation of glucose transport in terms of a pore.
Level 5 - mechanism / opinion, no new human data
In vitro laboratory study of red blood cells and theoretical kinetic modeling (bench research).
PubMed 856270 · doi:10.1016/0005-2736(77)90209-7
What was done
Formulated a theoretical alternating-conformation pore model for erythrocyte glucose transport to distinguish it from mobile carrier models. To test whether non-specific solute permeability scales inversely with molecular size, researchers measured the glucose-dependent permeability of 4-carbon (erythritol), 5-carbon (D-arabitol, L-arabitol, xylitol), and 6-carbon (D-mannitol, D-sorbitol, myo-inositol) polyols in human red blood cells.
What was found
The abstract reports no exact numerical values for permeability rates, inhibition constants, or pore dimensions. The permeability of all tested polyols was decreased in the presence of glucose, with an inhibition constant (KI) similar to that of D-sorbose. The glucose-inhibitable permeability decreased as polyol molecular size increased, matching the prediction of the pore model.
Why it matters
Provides biophysical evidence that red blood cell glucose transport can be explained by a conformational pore mechanism rather than requiring a mobile carrier.
Limits
The abstract reports no sample sizes, exact numerical data, or statistical variance. The in vitro findings cannot completely rule out an alternative carrier model with graded polyol binding affinities.
Cited by
- context Glucose-derived polyols such as sorbitol and mannitol cannot passively cross cell membranes.