Search

Biologic membranes display rectification of electrical current, as well as other properties, in many respects, similar to precipitation membranes. The experiments reported here, performed in frog skin, show that these characteristics are dependent upon the presence of calcium. Upon elimination of calcium from the bathing solution, the property of electrical rectification is lost, the current-voltage relation assuming a linear form. Read-ministration of calcium brings about complete recovery of the rectification pattern. This behavior is analogous to chemical deconditioning of precipitation membranes. Our findings support the assumption that the binding of calcium in biologic membranes produces electrical effects characteristic of precipitation membranes. [ABSTRACT FROM AUTHOR]

Precipitation membranes, like biological membranes, are specifically impermeable to certain ions. This property can easily be removed (deconditioning of the membrane) and restored again (reconditioning). The assumption is that special properties of the membrane are due to ion charges, adsorbed on precipitate layers. In this paper we study the deconditioning of the BaSO precipitation membrane by an imposed electrical field. To achieve this electrical deconditioning, a threshold potential across the membrane has to be surpassed during a certain minimum of time. If this is done, the membrane potential of the conditioned precipitation membrane is lowered to the sum of the liquid junction potentials in the system in absence of an ion barrier. The rectification action of the membrane is lost, too. After switching off the imposed field, a spontaneous reconditioning takes place. The readjustment of both the membrane potential and the rectifying properties were followed. The first phase of reconditioning is obviously diffusion-controlled. All the results reported confirm the assumption stated above. The phenomena described can easily be explained as caused by the removal and the readjustment of adsorbed ions. [ABSTRACT FROM AUTHOR]