Phosphorylation of sodium channels by PKC decreased whole-cell Na⁺ current and slightly delayed inactivation. A, Administration of the PKC activator PMA (1 μm) decreased peak Na⁺ current. B, The traces inA have been rescaled such that current amplitude is normalized in the two conditions. This allows better detection of the slower inactivation in the presence of PMA. However, this effect was observed in only four of nine neurons. C, The voltage dependence of activation was not altered by PMA treatment (n = 3). D, The voltage dependence of inactivation was not altered by PMA treatment (n= 3). See Figure 5 legend for details of activation and inactivation curves.