Excitation of squid giant axons below 0 degree C.

The excitation of the squid giant axon that had been perfused intra- and extracellularly with solutions containing a high concentration of glycerol could be observed below 0 degree C. The action potential could be elicited at normal strengths of electrical stimuli. The time-course of the action potential was slowed, whereas the resting potential and the amplitude of the action potential changed only slightly. The membrane current under the voltage clamp at -6.3 degrees C was about 100-fold slower than that in normal sea water at 8.7 degrees C because of the large viscosity of glycerol solutions and the low temperature. The Q10 values of the magnitude and the time-course of the membrane current were 2.3 and 1/4.0, respectively.