Essential biological processes such as osmoregulation and transmission of nerve impulses crucial-ly depend on translocation of water and ions through nanometre-sized membrane pores. In these processes, the electric fields, hydrodynamic interactions and osmotic gradients are inherently cou-pled, complicating theoretical analysis. Taking specific interactions between the channel surface and the ions into account, we solve the Stokes-Poisson-Nernst-Planck equations in a geometry based on the crystal structure of a large mechanosensitive ion channel. We show that the gating kinetics of such a simple model channel can be understood entirely in terms of the electrostatic and hydrodynamic stress, together with membrane elasticity. The broad applicability of this approach makes it a promising candidate for future physical modelling of a wide range of gated ion channels.