Models for electrical tuning in hair cells

We analyse several models for the electrical properties of vertebrate hair cell membranes to assess whether they can account for the electrical resonant tuning that these cells possess. The presence of either a voltage-gated potassium current or a calcium-gated potassium current in the cell membrane is shown, with suitable assumptions, to make the cell behave as a simple resistance-inductance-capacitance circuit showing resonant behaviour. With plausible values for the model parameters however, the presence of a voltage-gated current alone cannot account for the high Q values of the resonance behaviour seen in hair cells. A calcium-gated current could account for the high Q values. Mechanisms that allow variation of optimal frequency between different hair cells are discussed. It is concluded that the variation may be produced by systematic changes in the number of calcium channels and calcium pumps in the cell membrane.