Transport coefficients in a nonlinear series membrane array

Despite its many noticeable successes, several limitations of the linear thermodynamic description of membrane transport, as proposed by Kedem and Katchalsky, have been encountered. These arise as a consequence both of the various experimental non linear force-flow relationships found to date and of some intrinsic limits of the linear treatment. Suggestions intended to overcome the mentioned difficulties have been made by Patlak et al. and by Kedem and Katchalsky, utilizing series membrane arrays. Series arrays are particularly interesting as they approximate the structure of the epithelia and allow a correlation between the experimentally accessible global phenomenological coefficients of the array and the intrinsic characteristics of the single membranes. Some of these correlations will be analyzed in the following emphasizing the problems they pose in experiments.