Changes in action potential shape do not explain the decrease in Na⁺ entry and Na⁺/K⁺ current overlap with increases in temperature.

Abstract

<p>A. Action potential waveform occurring in the model axon at 18°C. B. Currents obtained from the model when the action potential in (A) was injected into the model, using ionic current kinetics obtained at 18°C. This result is the same as <a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1002456#pcbi-1002456-g001" target="_blank">Figure 1B</a>, 18°C. C–D. Running the model through the action potential waveform of (A), but with the channel kinetics of 27°C (C) or 37°C (D) results in a large decrease in Na⁺/K⁺ channel overlap (cf. B). E. Action potential waveform occurring in the model axon at 37°C. F. Injecting the action potential waveform in (E) into the model with Na⁺/K⁺ kinetics appropriate for 18°C results in a large inward Na⁺ current during the falling phase of the action potential, which overlaps extensively with the outward K⁺ current. G–H. Increasing the kinetics to those appropriate for 27°C (G) and 37°C (H) results in a large decrease in the overlap of Na⁺/K⁺ currents and the near disappearance of the Na⁺ current occurring during the falling phase of the spike (H). Dashed lines are aligned to the peak of the injected spike. See also supplemental <a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1002456#pcbi.1002456.s001" target="_blank">figure S1</a>.</p