Abstract
Electrophysiological methods have elucidated essential properties of ion channels. Basic principles of ion permeation through channel pore were reviewed. To investigate the physical picture of the pore, open channel blockers have been useful tools, providing cut-off size of the pore, location of the binding sites and geometry of the pore entrance. Examples are shown for the inward rectifying potassium channel, where the potential profile for Ba2+ blocking was characterized. Permeating properties of pores were described by either the discrete model or the continuum model.
