ION FLOW IN THE BATH AND FLUX INTERACTIONS BETWEEN CHANNELS

We present an exact solution to the linearized Nemst-Planck-Poisson eq uation for spherically symmetric current flow. This solution differs f rom Levitt's solution (Levitt, D. G. 1992. Biophys. J., Eq. A5) by its dependence on an additional parameter, which is equal to the net ion flux for monovalent ion-selective channels. For ion-selective channels , this solution may provide better boundary conditions to modelling th e flow in the channel pore itself, although only at low salt concentra tions. We use the solution to estimate the effects of flux interaction between closely packed channels.