Figure 3

Small diameter DRGs are unaffected by ATX-II or increased temperature. (a) The same stimulation protocol as used in large diameter DRGs was applied to small DRGs (upper lane). Example traces of TTX-s sodium currents pre and post 5 nM ATX-II application are shown. Lower lane displays an overlay of pre and post ATX-II traces at a voltage of −45 mV. (b) TTXs peak current at the time point at which resurgent currents would be expected as a function of voltage in small diameter DRGs. Neither at 22°C (filled symbols, n = 7) nor at 30°C (open symbols, n = 4) a significant ATX-II- induced resurgent current is evident (paired-sample T-test). (c) Mean persistent current as a function of voltage pre (black symbols) and post (pink symbols) ATX-II application. In small diameter DRGs there is no significant increase in persistent current detectable due to ATX-II exposure or heating to 30°C (paired-sample T-test). (d) Expression levels of β4, Nav1.6 and Nav1.7 mRNA normalized to the mean of two house-keeping genes in FACS-sorted small (white bars) and large (grey bars) DRGs determined by RT-qPCR. In large DRGs ß4 and Nav1.6 expression is twice as high compared to small neurons. On the contrary, Nav1.7 mRNA is evenly expressed in small and large DRGs (n = 3; * p < 0.05).