Sodium chloride reflection coefficient in rabbit gall bladder

Membrane selectivity in passive transport is measured by the reflection coefficient. In actively transporting membranes an apparent reflection coefficient has been introduced. The latter varies with experimental conditions. A relationship between the two coefficients has been derived. Assuming that distinct forces lead active and passive fluxes of the solute, the dissipation function can be written as a function of hydrostatic and osmotic pressure differences and of an "active force". From this a phenomenological equation for volumetric flow is derived. At volumetric flow = 0 the obtained equation well fit experimental data on NaCl transport in everted rabbit gall bladder.