Loss of excitability in isolated cerebral tissues, and its restoration by naturally occurring materials

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Abstract
Slices of guinea-pig cerebral cortex have been exposed to a variety of adverse conditions with the object of diminishing their respiratory response to electrical stimulation, while maintaining relatively normal respiratory rates in the absence of stimulation. The greatest differential effect occurred on exposure in tris-buffered glucose-containing media at 0[degree] for 5 hr. These conditions lowered also the tissue''s glycolytic response to electrical pulses and its respiratory response to high concentrations of K salts. Restoration of the exposed tissue''s respiratory response to electrical pulses was sought by adding a variety of substances to media in which the tissue was incubated. Additions included known metabolites, blood sera and extracts of brain, muscle and liver. Blood sera from several animal species were the most active of these materials in restoring respiratory response. Dialysis and solvent precipitation suggested that the activity was associated with the serum proteins. Examination of plasma fractions obtained by the method of ethanol precipitation of Cohn et al. (1946) showed the most active fraction to be IV-4, which contains [alpha]- and [beta]-globulin. The inorganic phosphate and phosphocreatine of cerebral tissues have been determined after the chosen conditions of exposure and after incubation with blood-protein preparations, and relationships between the exposed tissue and restorative agents have been discussed.