Transport numbers in biomembranes from emf measurements

Initial membrane potentials of biological periderm and cuticular membranes have been measured with KCl solution using Ag/AgCI electrodes. For the emf measurements, the concentration in both compartment were first brought to equilibrium with 0.01 M KCI solution. After equilibration the concentration in one compartment (inner surface of the membrane) was kept constant as 0.01 M and the concentration in the other compartment was varied between 10(-4) M and 1 M. The procedure was reversed as the concentration in the outer surface of the membrane was fixed and the other side was varied. Transport number of K(+) ion corresponding to the each of the two surface layers (homogeneous and heterogeneous) of the membrane was evaluated from the initial time emf measurements. The results obtained were compared with charged polysulfone with polyester supported membrane.