Extracellular release of cerebral macromolecules during potassium- and low-calcium-induced seizures.

Cerebral cortex of cat was incubated with 14C-lysine and 3H-glucosamine. Subsequent superfusion of the surface of the cortex resulted in the release into the superfusate of a variety of 14C- and 3H-labeled compounds including proteins, glycoproteins, and gangliosides. The release of 14C- and 3H-labeled macromolecules could be considerably enhanced by topical addition of 40 mM K+, WHICH INDUCED Epileptiform EEG activity. Peaks in efflux could also be correlated with the onset of seizures induced by superfusion with low (0.75 mM) Ca2+ media. Control experiments in which the cortex was prelabeled with 14C-carboxyl-inulin and 3H2O indicate that the release of macromolecules was not a direct consequence of the altered blood flow that may occur during convulsions.