Specific binding of [3H]phenytoin in the human brain

Competition between cold phenytoin and [3H]phenytoin binding was observed in normal human brain. Binding was observed in all areas examined. The highest number of sites was in the amygdala (a total of 717.71 fmol/mg protein) and the lowest in the Brodman area (BA) 4 of the motor cortex (153.91 fmol/mg protein) and cerebellar cortex (154.4 fmol/mg protein). In three areas, amygdala, cortex area BA 38 (inferior parietal lobe), and cortex area BA 8 (premotor cortex), two sets of binding sites were observed. In these areas the Kd for the higher affinity sites ranged from 35 to 116 nM, and for the lower affinity site, from 328 to 866 nM. In the four areas where only one binding site was observed the KdS ranged from 164 to 311 nM and the Scatchard plot was linear.