THE EFFECTS OF PHENOBARBITAL UPON PHOSPHATE METABOLISM OF CEREBRAL CORTEX IN VITRO

¹ Department of Biochemistry, Institute of Psychiatry, Maudsley Hospital, Denmark Hill, London, S. E. 5, England
² Division of Neurology, University of Minnesota, Minneapolis 14, Minnesota

The effect of phenobarbital at concentrations ranging from 5 to 17 x 10^-4 M has been studied upon the respiration and phosphate metabolism of slices of guinea pig cerebral cortex in the presence and absence of electrical impulses.

Increasing concentrations of phenobarbital brings about an increasing suppression of electrically stimulated oxygen uptake, the suppression being complete at 1.7 x 10^-3 M. No suppression of unstimulated oxygen uptake occurred at this concentration.

Phenobarbital at 1.7 x 10^-3 M had no significant effect upon the rate of resynthesis of phosphocreatine which proceeded at 130 to 140 µmols/g wet wt/hr; however, it partly protected against the depletion of phosphocreatine normally brought about by electrical pulses. The protective effect was noticeable at 8.5 x 10^-4 M phenobarbital.

At 1.7 x 10^-3 M phenobarbital enhanced the specific radioactivity of phosphocreatine, adenosine triphosphate and phosphoprotein in cerebral slices metabolizing radioactive phosphate.

These results indicate that phenobarbital does not impede the synthesis of energy-rich phosphates, but does interfere with their utilization.