DYNAMICS OF FORMATION AND DISSIPATION OF LOCAL PH GRADIENTS IN THE UNSTIRRED LAYERS NEAR BILAYER-LIPID MEMBRANES

The kinetics of formation and dissipation of pH shifts in the unstirre d layers near planar bilayer lipid membranes (BLMs) induced by a volta ge step in the presence of a protonophore was studied. The pH gradient s were monitored by measurements of the tetrachlorotrifluoromethylbenz imidazole (TTFB) mediated current and the open-circuit BLM potential. Nigericin in the presence of potassium ions was used to affect the dyn amics of pH relaxation. The open-circuit voltage caused by the pH shif ts can be linearized in coordinates of the potential vs. the square ro ot of time. The current through the BLM after the application of a vol tage step was linear in the coordinates of normalized current vs. the inverse square root of time.