Figure 4. R424H mutant-expressing PCs exhibit suppressed peak outward current density.

A, representative outward current traces recorded from PCs expressing GFP alone (Aa), WT subunits (Ab; note the vertical scale bar) and R424H mutant subunits (Ac). The currents were evoked by voltage steps from the −70 mV holding potential to voltages ranging from −60 to +40 mV in 10 mV increments. Leak currents were subtracted online by the P/4 protocol. The currents were recorded at DIV 8–10 in Hepes-buffered srtificial cerebrospinal fluid (ACSF) containing TTX, CdCl₂, picrotoxin and 6,7-dinitroquinoxaline-2,3-dione (DNQX). B, summary of the peak outward current density, which was calculated by dividing the peak outward current by membrane capacitance. **P < 0.01 and ***P < 0.001.