Experimental evaluation of a thermodynamic model for non-linear volume flow in rabbit gall bladder

The non-linear dependence of volume flow across the rabbit gall bladder on the osmotic pressure difference of both an impermeant (sucrose) and a permeant (NaCl) solutes is described by means of a series membrane model. The transport coefficients, besides being combinations of the ones relating to the single membranes, are shown to be markedly non-linear functions of the experimental conditions. A method is shown for the experimental determination of the reflection coefficients pertaining to the individual membranes and for the subsequent calculation of the other phenomenological coefficients. The analogies between the present model and the classical linear description are discussed. It appears that the latter can be used as a first approximation of the former.