Figure 2.

Kcna1 ^−/− mice exhibit a fivefold increase in basal AV blocks, a difference that is exacerbated by seizure activity. A, Comparison of mean number of AV blocks per hour during interictal periods in wild-type and null mice (n = 4 per genotype) showed a fivefold increase in mutants. During seizures in null mice, the frequency of AV blocks increased another fivefold to 25 times the wild-type rate. B, Histogram distribution of interictal AV blocks per hour in wild-type and null mice during 24 h recording sessions (n = 4 mice per genotype) shows that wild-type mice usually exhibited only 0–2 conduction blocks per hour compared to null mice, which exhibited conduction blocks with much higher frequency, up to 15 or more per hour. At least one AV block was observed in 96% of recording hours in null mice, whereas less than half of the recording hours showed a conduction block in controls. *p < 0.001; two-tailed t test.