Temperature effects on the properties of the Hodgkin-Huxley propagated action potential model determined by computed solutions and phase-plane analysis.

The equation for membrane potential (V) of the squid giant axon or some muscle cells, which is the heart of the Hodgkin-Huxley model for the action potential, can be written in three ways: first, as a partial differential equation in time and space; second, as an ordinary differential equation in time, assuming uniform wave propagation for the action potential, and third, as an even simpler ordinary differential equation for the potential at a point, so-called "space clamp" conditions. Solutions were computed for the first two of these equations, at three different temperatures, and the results compared. Temperature dependence of the appropriate parameters was calculated from a simple exponential relationship. Significant changes in the quantitative predictions of the model were found as the temperature was changed from 6.3 C to 18.5 C. Phase-plane (V v V, I v V) analysis has been used to examine the nature of these differences.