Patent ID: 6991910

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 Na + -free physiological buffer; ii) a voltage-sensitive fluorescence dye; iii) a cell having a K + channel, a transient Na + channel and a persistent Na + channel; and iv) a potential Na + channel blocker; b) depolarizing membrane of the cell in the test sample 1 ; c) generating a current through the persistent Na+ channel by adding Na + to test sample 1 at least 10 msec after step (b); d) detecting fluorescence emitted by the voltage-sensitive dye in test sample 1 ; e) providing a control sample 1 comprising i) a Na + -free physiological buffer; ii) a voltage-sensitive fluorescence dye; and iii) a cell having a K + channel, a transient Na + channel and a persistent Na + channel; f) depolarizing membrane of the cell in the control sample 1 ; g) generating a current through the persistent Na + channel by adding Na + ions to the control sample 1 at least 10 msec after step (f); h) detecting fluorescence emitted by the voltage-sensitive dye in the control sample 1 ; i) determining the relative emitted fluorescence 1 by comparing the emitted fluorescence from step (d) to the emitted fluorescence from step (h); j) providing a test sample 2 comprising i) a physiological buffer; 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 k) depolarizing membrane of the cell in test sample 2 ; l) detecting the fluorescence emitted by the voltage-sensitive dye in test sample 2 ; m) providing a control sample 2 comprising i) a physiological buffer; ii) a voltage-sensitive fluorescence dye; and iii) a cell having a K + channel and a transient Na + channel; n) depolarizing membrane of the cell in control sample 2 ; o) detecting the fluorescence emitted by the voltage-sensitive dye in control sample 2 ; p) determining a relative emitted fluorescence 2 by comparing the emitted fluorescence from step (l) to the emitted fluorescence from step (o); q) comparing the relative emitted fluorescence 1 in step (i) with the relative emitted fluorescence 2 in step (p).