Figure 3.

Phenotypic effects of activation of the conditional allele by ubiquitously expressed EIIa-Cre. (A) Scn8a^cond/+ heterozygotes expressing EIIa-Cre exhibited sudden lethality at the end of the second week of life, with median survival of 15 days. Scn8a^cond/+ heterozygotes that did not inherit EIIa-Cre exhibited normal life span. (B) EEG recording of a fatal seizure in an Scn8a^cond/+,EIIa-Cre mouse on P15. The recording was obtained from bipolar insulated stainless-steel electrodes in the left parietal cortex (top trace) and right parietal cortex (second trace). The EMG artefact in the third trace reflects the period of running evolving to tonic extension. Death occurred 3 min 20 s after the onset of running. The bottom trace was obtained from an electrode placed subcutaneously in the right thorax and demonstrates sudden slowing of the heart rate from 756 bpm prior to the running fit to 156 bpm immediately afterwards.