Physiological Adaptation to Cold of Peripheral Nerve in the Leg of the Herring Gull (Larus Argentatus)

Abstract

Herring gulls maintained in a cold environment showed marked differences in the internal temps. of the metatarsal and tibial parts of their legs. Peripheral nerve isolated from the metatarsus conducted impulses at significantly lower temps. -than nerve from the tibial portion. This difference was most pronounced in gulls that had been maintained at low environmental temps., and least pronounced in gulls forced to wade in a pan of water at 37[degree]C. This resistance to cold was not observed in nerves from domestic hens, whose legs differ in structure and do not show the temp. gradient found in gulls. Maximal conduction velocity in gull nerves was about 25 m./sec., in hen nerves 100 m./sec. On cooling gull nerves, there were linear decreases in conduction velocity and in excitability, whereas the height of the compound action potential passed through a maximum which occurred at a lower temp. in nerves from the metatarsal portion of the leg than in those from the tibial portion. Thus peripheral nerve in the gull shows an adaptation to cold. Histochemical study revealed no differences in chemical morphology between tibial and metatarsal portions of the nerves.