FURTHER INVESTIGATIONS ON EFFECT OF ANOXIA ON CONVULSIONS

Abstract

Normal and adreno-demedullated rats anesthetized with pentothal show a greater susceptibility to electroshock-induced convulsions in moderate degrees of anoxia (280 mm. Hg for 10 min.) than at normal barometric pressure. Unanesthetized rats shocked at a stage of anoxia when the righting reflexes are lost (120-155 mm. Hg ), respond more frequently with convulsions and show more severe convulsions than under control conditions. Severe anoxia leading to functional elimination of cortex and brain stem and the occurrence of gasping reduces the susceptibility to convulsions. On the basis of earlier expts. it is suggested that the increased susceptibility to convulsions in moderate anoxia is related to the release of subcortical structures. However; severe anoxia in which cortex and brain stem are similarly depressed shows, for generalized convulsions, that anoxia inhibits convulsive activity. Under these conditions the remaining functioning parts of the central nervous system (medulla oblongata and spinal cord) behave like the cortex after local strychniniza-tion.