Figure 3. Sodium currents in GEFS+ and control LNs. A, A LN in the dorsal lateral cluster in the antennal lobe, filled with biocytin during recording, in a control and GEFS+ brain. Confocal images of the brains fixed and double stained with a fluorescently labeled secondary antibody to biocytin and Nc82 (anti-bruchtpilot antibody) are shown. Arrows indicate the LN cell body (control) or axon initial segment (GEFS+). The soma of the GEFS+ cell was lost during pipette removal. B, Depolarizing voltage-step-elicited sodium currents at room temperature (23°C) and following heating of the recording solution to high temperature (35°C). INaP in control LNs decayed to baseline after the pipette potential returned to −75 mV, but it remained activated in the GEFS+ LN at 35°C (arrow). Sodium currents could not be clamped in either genotype. C, INaT amplitudes are no different in GEFS+ and control LNs at 23 or 35°C (independent t test, 23°C, p = 0.28; 35°C, p = 0.07), and the amplitude did not change with temperature in either genotypes (paired t test, control, p = 0.08; GEFS+, p = 0.20). D, The voltage step required to elicit the first inward sodium current is significantly more hyperpolarized in GEFS+ than in control at both 23 and 35°C. ***p < 0.001 (independent t test). The current activation threshold did not change significantly with temperature in either genotype (paired t test, control, p = 0.06; GEFS+, p = 0.14). Symbols and error bars represent mean ± SEM.