The effects of certain anaesthetic and anti-convulsant drugs on the CSF potassium fluxes of the dog.

1 A technique has been developed for open-ended perfusion of the cerebroventricular system of the unanaesthetized dog.2 Perfusion with an artificial CSF solution containing inulin and (42)K allowed the potassium fluxes out of and into the CSF to be monitored over a period of 2 to 3 hours.3 Sodium thiopentone and sodium pentobarbitone, in doses producing light anaesthesia, caused varying degrees of depression (up to 50%) in the CSF potassium fluxes, influx being consistently more affected than efflux. These effects are attributed to a decrease in the potassium exchange between extracellular and intracellular compartments in the brain.4 Diazepam depressed both potassium fluxes by up to 10% while there was some evidence that diphenylhydantoin depressed only potassium influx.5 Paraldehyde, in contrast to the other drugs, when given at a dose level sufficient to produce light anaesthesia, stimulated CSF potassium fluxes, particularly efflux.