Fig. 1. Representative voltage-clamp recordings of Na+currents. ( A ) Tetrodotoxin (TTX)-sensitive Na+currents endogenously expressed in an ND7/23 cell in the absence ( left ) or presence ( right ) of 300 nm tetrodotoxin, which is sufficient to block all tetrodotoxin-sensitive Na+channels without affecting Nav1.8. 3 ( B ) Recordings of an ND7/23 cell transfected with Nav1.8 in the absence ( left ) or presence ( right ) of 300 nm tetrodotoxin, which blocks tetrodotoxin-sensitive Na+channels and results in pharmacological isolation of the tetrodotoxin-resistant Nav1.8 current. Inset shows stimulation protocol, Vh=−70 mV, voltage steps from −80 to +70 mV; pulse duration, 5 ms.