Ball and chain model of inactivation process of some of the ion channels is resolved by means of diffusion (hyperbolic and parabolic operators). Polypeptide ball --- a part of the channel's protein that is responsible for inactivation, is treated as a Brownian particle tethered on polypeptide chain. First passage time of the ball is calculated and compared with experimental data. It is shown that diffusion provides an insight into the mechanism of inactivation process in agreement with experimental data.

PACS numbers: 87.15.Vv, 87.16.Uv