Effects of cooling on nerve conduction in a hibernator, golden hamster, and non-hibernator, albino rat.

ITTLE attention appears to have been paid in recent years to neurophysioL logical differences between mammals capable of hibernation and those that are not. Horvath (I) pointed out that certain species (ground squirrel, hedgehog, European hamster, and bat) could be cooled artscially until their rectal temperatures approached 0°C. and still revive spontaneously on being returned to a warmer environment. On the other hand cooling to a rectal temperature of IO' to 19°C. is usually fatal to mammals which do not hibernate, for example, rabbits, cats, dogs, guinea pigs, rats and monkeys (2-Q, although mice have survived a body temperature of 8.5OC. (9) and newborn rats have recovered from 5OC. (IO). Interest was aroused in the present problem when it was noted that hibernating golden hamsters with body temperatures of 4OC. as measured by rectal and cheek pouch thermocouples still responded to external stimuli. Since it had been shown that nerves of the cat studied in vitro cease functioning at about 8OC. (XI), it was thought advisable to compare the effects of cooling on conduction by nerve in the hamster and a non-hibernating rodent, the albino rat.