Patent ID: 8421484

Claim:
A method for measuring a change in membrane potential in a mammalian cell having an ion channel, said method comprising: (a) measuring the resting impedance in the alpha dispersion frequency range of a mammalian cell having the ion channel; (b) exposing a mammalian cell having the ion channel of the cell of step (a) to a test agent; (c) measuring the impedance in the alpha dispersion frequency range of the cell of step (b); and (d) calculating the change in the membrane potential of the cell upon exposure to the test agent, wherein calculating comprises: (i) determining the shape of the cell; and (ii) determining the change in the membrane potential based on fitting the measured impedance with the theoretical model: ɛ sus ⁡ ( ω ) = ɛ 0 * ⁡ ( 1 + p ⁢ ⁢ α ⁡ ( ω ) 1 - p ⁢ ⁢ α ⁡ ( ω ) / 3 ) , ⁢ with ⁢ ⁢ α _ ⁡ ( ω ) = 1 VE 0 ⁢ ∫ V ⁢ ⁢ ⅆ V ⁢ ɛ * - ɛ 0 * ɛ 0 * ⁢ 〈 E _ ⁡ ( ω ) 〉 , wherein ∈* 0 is the complex dielectric function of the medium, p is the volume concentration of the solution, α(ω) is the frequency dependent polarizability, V is the volume, Ē 0 electric field of amplitude ∈* is the non-uniform complex dielectric function of the composite particle, and Ē(ω) is the electric field inside the particle.