Figure 3. Effects of body size and Q₁₀ on thermogenesis and HR during ambient cooling.

A and B, WT animals (filled circles, nos. 1–5) weigh more than Pet-1^−/− animals (open circles, nos. 6–10), and mass has a significant relationship with T_B and (2-factor repeated-measures ANOVA: P < 0.05 for each). C and D, and HR after cooling (normalised to baseline values) for WT (filled bars), and Pet-1^−/− (open bars). Shown are observed values and values predicted from the Q₁₀ effect alone (assuming Q₁₀ co-efficient of 2 and with a drop in T_B of 4.2°C in Pet-1^−/− and 3.1°C in WT). Data in C and D are means ± SE. *Significant difference exists between observed WT values for and HR and the values predicted from the Q₁₀ effect alone. No such difference exists between the observed and predicted values for Pet-1^−/− animals.