THE MECHANISM OF GLUCOSE TRANSFER INTO AND OUT OF THE HUMAN RED CELL

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  • 1 January 1952
    • journal article
    • research article
    • Vol. 35  (6) , 891-906
Abstract
Earlier observations concerned with the kinetics of the penetration of the human erythrocyte by glucose were extended to include glucose exit from the cell as well as its entry, with the widest variety in the relations between several quantitative factors contributing to the glucose gradient and resultant osmotic volume changes. For example, the initial cell volume or glucose level, the extracellular glucose concn., or the initial gradient, or the total glucose transfer or volume change, were each held constant while other factors were varied, and the volume changes recorded ([PHI]rskov method). Provided the glucose level in the medium did not exceed about 75% isosmotic, all records showed patterns compatible with a "carrier" system involving reversible complex-formation between glucose and a cell surface component, by simple mass action. The complex must be highly undissociated and the reactions much faster at the outer than at the inner interface of the cell surface phase. This means that the rate of transfer in either direction is proportional to the gradient, at a fixed extracellular glucose level; but inversely proportional to the extracellular concn., with a fixed gradient; and that the inward rate is limited, while the outward rate may be much faster. This simple system gradually fails to operate as the glucose level in the medium is raised above 75% isosmotic; this inhibition is reversible. An empirical correction is derived for a known but hitherto uncalibrated optical disturbance complicating the use of non-electrolyte solns. in the 0rskov apparatus.

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