Fig. 4.

Temperature coefficients Q₁₀ for cardiac dynamic properties in rabbit and alligator across BCLs for which hearts could be stimulated at both 23°C and 38°C. (A) The Q₁₀ of APD in alligator approaches unity across all BCLs. In rabbit, APD is more greatly affected by the temperature at larger BCLs. (B) CV in rabbit is increasingly sensitive to temperature as BCL is reduced, and CV in alligator shows small temperature sensitivity across all BCLs. (C) Action potential wavelength ${\lambda }_{\text{APD}}$ in alligator is insensitive to temperature across all BCLs. This wavelength in rabbit exhibits strong temperature sensitivity, exacerbated further as BCL is reduced. (D and E) Q₁₀ for all coefficients overlaid for each species. In rabbit (D), Q${}_{10}^{\text{CV}}$ and Q${}_{10}^{\text{APD}}$ become increasingly unbalanced at shorter BCLs, whereas in alligator (E), temperature sensitivities of APD and CV coordinate and preserve a temperature-insensitive ${\lambda }_{\text{APD}}$ across BCLs. Error bars denote 1 SD. Colored traces in A–C denote linear regressions with slopes listed in plots.