The effect of diphenylhydantoin on spreading depression.

The present study examines the effect of diphenylhydantoin on the elicitation by K+ and propagation of spreading depression in chick retina preparations in vitro. A dose-related decrease in the velocity of propagation was observed, this effect being lessened by increasing the pH of the Ringer bathing the preparation. Changes in Ringer Cl- concentration also altered the efficacy of the drug, higher concentrations enhancing and lower concentrations reducing efficacy. The threshold concentration of K+ necessary to elicit the reaction was elevated by diphenylhydantoin.