Influence of ionic disturbances produced by gastric washing on cortical spreading depression.

The ionic composition of the internal environment was altered in rabbits by means of gastric washing, combined with intramuscular administration of 3-Beta-aminoethylpyrazole. The effects of this treatment on cortical spreading depression (SD) were studied. Cl- and Na+ concentrations decreased significantly in serum and in cerebrospinal fluid after the treatment. This made the animals much more susceptible to SD, as established by the high incidence of "spontaneous" SD, increased SD velocity of propagation and facilitated its interhemispheric transfer. An intensification of the epileptiform activity associated with SD was also observed. Intravenous replacement of NaCl abolished the above effects of SD. When the intravenous replacement was done with Na-Isethionate, those effects were enhanced. It is concluded that chloride deficiency was the main factor responsible for the observed facilitating effects.