Patent ID: 7723053

Claim:
A method for identifying a selective blocker of a persistent Na + channel whereby the method comprises the steps of: a) providing a test sample 1 comprising i) a Cl − -free physiological solution; ii) a voltage-sensitive fluorescence dye; iii) a cell having a K + channel and a persistent Na + channel wherein a K + conductance of the K + channel is at least 50-fold higher than a Na + conductance from the persistent Na + channel; and iv) a potential Na + channel blocker; b) depolarizing the membrane of the cell with a Na/K pump blocker in test sample 1; c) detecting fluorescence emitted by the voltage-sensitive dye in test sample 1; d) providing a control sample 1 comprising i) a Cl − -free physiological solution; ii) a voltage-sensitive fluorescence dye; and iii) a cell having a K + channel and a persistent Na + channel wherein a K + conductance of the K + channel is at least 50-fold higher than a Na + conductance from the persistent Na + channel; e) depolarizing the membrane of the cell with a Na/K pump blocker in control sample 1; f) detecting fluorescence emitted by the voltage-sensitive dye in the control sample 1; g) comparing the emitted fluorescence from step (c) to the emitted fluorescence from step (f); h) providing a test sample 2 comprising i) a physiological solution; ii) a voltage-sensitive fluorescence dye; iii) a cell having a K + channel and a transient Na + channel; and iv) a potential Na + channel blocker i) depolarizing the membrane of the cell in test sample 2; j) detecting the fluorescence emitted by the voltage-sensitive dye in test sample 2; k) providing a control sample 2 comprising i) a physiological solution; ii) a voltage-sensitive fluorescence dye; and iii) a cell having a K + channel and a transient Na + channel; l) depolarizing the membrane of the cell in control sample 2; m) detecting the fluorescence emitted by the voltage-sensitive dye in control sample 2; n) comparing the emitted fluorescence from step (j) relative to an emitted fluorescence from step (m); o) comparing the difference in step (g) with the difference in step (n); wherein a decrease is emitted fluorescence from step (g) relative to the emitted fluorescence in step (n) is indicative of the presence of a selective persistent Na + channel blocker in the test sample.