Fig. 2.

Occurrence of arrhythmias during a torpor bout in thirteen-lined ground squirrels. The level of arrhythmias was measured by calculating the interbeat interval (IBI) coefficient of variation (COV) for 8 squirrels during the first seasonal torpor bout at 5°C (A). Arrhythmic patterns occurred more frequently as squirrels entered and maintained a torpor bout and less frequently during the arousal phase. Groups shown to be statistically different by an ANOVA followed by a Tukey's test do not share the same letter above the bar. B: example of the changes in IBI COV (black) relative to the changes in heart rate (pink). For comparison, the same animal is used as an example as in Fig. 1.