The binding of [3H]thienyl cyclohexylpiperidine ([3H]TCP) to the NMDA-phencyclidine receptor complex

The high affinity binding of the phencyclidine derivative [3H]TCP to cortical membranes of the rat was investigated. In an extensively washed membrane preparation the binding of [3H]TCP was enhanced in the presence of L-glutamate and NMDA. The stimulation of the binding of [3H]TCP by L-glutamate was inhibited competitively by AP5 and non-competitively by MK801. The binding of [3H]TCP was also enhanced in the presence of glycine; this effect was insensitive to strychnine and inhibited non-competitively by AP5. Saturation experiments demonstrated that MK801 was a competitive inhibitor of the binding of [3H]TCP. These results suggest that [3H]TCP binds to a site similar to that which binds MK801; this site may be associated with the ion channel of the NMDA receptor.