HIGH-LEVEL STABLE EXPRESSION OF RAT-BRAIN TYPE-IIA SODIUM-CHANNEL ALPHA-SUB-UNIT IN CHO CELLS

The neuronal sodium channels are responsible for the rising phase of a ction potential and are composed of three subunits, of which the alpha -subunit has been shown to be adequate for most of its functional prop erties. We have stably expressed the rat brain type IIA sodium channel alpha-subunit in CHO cell tine using a CMV promoter-based vector. The expression was confirmed by detecting a 6.5 kb RNA corresponding to s odium channel alpha-subunit using Northern hybridization. The cells st ably expressing the alpha-subunit, yield isolated sodium currents of a mplitudes greater than 4nA when studied in whole-cell configuration of the patch-clamp technique. The sodium currents are characterized by a ctivation and inactivation properties similar to neuronal sodium chann els, and are blocked by the voltage gated sodium channel blocker tetro dotoxin (TTX).