Precipitation membranes: III. Reversible changes of membrane properties induced by alterations in ionic concentrations

Abstract

The conditioned state of a precipitation membrane with its particular properties exists within a limited range of membrane potentials and requires certain minimum concentrations, Clim, of the generating ions in the adjoining solutions. We investigated these quantities for the BaSO4 cellophane membrane and found Clim to be 10 X 10(-5) N (0.5 X 10(-4) M), equally for Ba++ and SO4--. Beyond these limits, the membrane becomes deconditioned. This transformation is a reversible process provided the limits have not been surpassed too far. The capability for de- and reconditioning is a characteristic and unique property of precipitation membranes, not found in other membrane systems. The phenomenon is explained by the adsorption theory for precipitation membranes. It allows wide modifications and quick variations of the electrical properties and permeability of the membrane in an easy and reversible manner.

Precipitation membrane effects in biologic membranes: The role of calcium

“…In this study we show that electrical rectification in the frog skin depends on the presence of calcium and reversibly disappears upon its removal from the external bathing solution. In precipitation membranes the characteristic rectification pattern similarly converts into a linear function upon the reduction of the concentration of their generating ions to below a certain minimum (Hirsch-Ayalon, 1979). These findings support the assumption that the binding of calcium in biologic membranes produces electrical effects characteristic of precipitation membranes.…”

“…These charges are not fixed, however, and can easily and reversibly be desorbed. Desorption, and thus deconditioning, can be brought about by the reduction of the concentration of one of the generating ions to below a certain minimum (Hirsch-Ayalon, 1979), or by the application of a depolarizing potential which draws the charges away from the precipitate (Bfihr & Hirsch-Ayalon, 1974). The characteristic rectification pattern, in both instances, transforms into a linear I,A 7~-relation.…”