Effect of Temperature Change on the Cochlear Potentials of the Guinea Pig

Abstract

Hypothermia was induced by surface cooling in 32 anesthetized guinea pigs' and the effects upon AP, SP, CM and EP of the cochlea were examined. The amplitude of the CM was almost linearly descreased and the latency of the AP was increased as a function of temperature decline. The SP showed variable changes, but this potential still remained when the other potentials were absent. The change of the AP amplitude was the most interesting finding in this experiment. It showed no change or transient increase up to 28°C, followed by gradual decrease with the further temperature decline. The EP was slowly decreased from 36°C to 27°C and rapidly decreased thereafter. The decline of EP in anoxia for 120 sec was decreased as the temperature was lowered. These results are relevant to the animal experiments reported by the others, and they show that hypothermia induced the diminution in the metabolic activity in all cochlear tissue.