Effects of temperature on membrane potentials of lobster giant axon

Abstract

In the range 2–20 C, the resting potential of the lobster axon shows a greater increase with increase of temperature than can be explained by the Nernst relationship. Action potential also shows an initial increase with temperature, peaks at about 16 C, then decreases. Maximum rates of rise and fall of the action potential increase with temperature increase; duration of the propagated action potential decreases. Afterpotentials in this preparation are in the form of a delayed repolarization; as temperature is increased, the magnitude of the afterpotentials increases, as does the rate of repolarization. These results have been compared with results already available for the squid axon. Differences between the two preparations occur in the relationship of the resting potential, action potential magnitude, and afterpotentials to temperature. It is suggested that these differences may be explained by the presence of a temperature-dependent fraction of the resting potential in the lobster axon which is not present, or is inactive, in the squid axon.