Diffusion through a cluster of small windows and flux regulation in microdomains

The way the arrangement of small conductors of ionic current on biological membranes regulates flux is an open physical question. We study this problem by a model of diffusion through a cluster of channels in an impermeable biological cell membrane. We show that the flux depends on the relative distance between the channels and show that moving two contiguous channels apart may increase the flux by nearly 50%. Brownian simulations in 2 and 3 dimensions agree with the theoretical results. (C) 2008 Elsevier B.V. All rights reserved.