| Comments |
"For sugars which are transported by a saturable path, a true permeability P cannot
be calculated. Permeability calculated at an infinitesimal concentration of the sugars,
where no saturation is effective, however, would provide a unique measure of relative
permeation by different permeants. This permeability at an infinitesimal concentration
of the permeant is obtainable by taking the first derivative of the classical Michaelis-
Menten expression of the carrier-mediated flux (Wilbrandt & Rosenberg, 1961) with
respect to the permeant concentration, at the condition of zero permeant concentration,
(Vmax/Km), then dividing by the total surface area of the cells. The values of 1.55x10^-6cm^2 and 8.7x10-11cm^3 were adopted for the surface area and the volume, respectively,
of a single human red cell (primary source)." |