Effect of convulsive activity upon the concentration of brain glucose, glycogen, lactate, and phosphates.

The effect of convulsive activity of brain upon its composition is not clear. It has been reported that convulsions induced by metrazol (l-3), picrotoxin (l), and cyanide (1, 4, 5) are accompanied by increases in brain lactate, while those induced by strychnine are not (3). A decrease in brain glycogen is reported to occur during seizures induced by picrotoxin and strychnine (6); however, the assay of glycogen used was probably inadequate (3). Further, it has been reported that convulsions induced by picrotoxin, metrazol, and strychnine do not affect the concentrations of glucose, glycogen, or phosphocreatine in brain (3). This conclusion was based on experiments in which the convulsions were terminated by administration of amytal or ether some time before removal of brain for analysis. Anesthesia is reported to lead to maximum concentrations of high energy phosphates (7) and minimum concentrations of lactate (1, 7), which suggests that the several negative tindings may have been due to reversal, during the period of anesthesia, of changes which had been effected by the convulsions. This suggestion is borne out by the observation that, under continuous morphine anesthesia, convulsions induced by metrazol are accompanied by a decrease in brain phosphocreatine (2). In addition to an increase in lactate, administration of cyanide is followed by decreases in brain glycogen (4), phosphocreatine (4, 5), and adenosine triphosphate (4). However, convulsions induced by cyanide are due to depression of the cerebrum with consequent release of lower structures. Thus, the changes in composition of brain induced by cyanide are not directly comparable to those produced by the other drugs considered, since they increase the activity of the cerebrum. The present work reports t,he effect of induced convulsive activity of brain, defined by its electrical activity, on the concentration of glucose, glycogen, lactate, and phosphates in the cerebral hemispheres of paralyzed cats maintained with artificial respiration. The experimental conditions