Cerebral impedance changes in hypothermia

Abstract

In rabbits and rats impedance changes in the cerebral cortex after circulatory arrest were measured at 37° C. and 28° C. body temperature. The onset of impedance rise is retarded by cooling, but once begun, impedance rise and chloride movements take place with the same speed and in the same way at both temperatures. The latent period was prolonged from 3.5 to 5 minutes in rabbits and from 1 to 4.5 minutes in rats. A relation between depolarization and creatine-phosphate level is postulated at 37° C., whereas at 28° C. another limiting factor may intervene. The histochemical method for chloride ions suggests that at 28° C. apical dendrites contain less chloride than at 37° C.