Specific binding of [ 3H]diazepam in mouse glioblastoma the influence of clonazepam and Ro 5–4864 on [ 3H]diazepam binding

The reversible specific binding of [ 3H]diazepam was observed by a radioligand method in homogenates of cultured cells of mouse glioblastoma. It was characterized by an equilibrium dissociation constant K d = 91 ± 5 nM and the number of maximal binding sites (B max) of 1006 ± 100 fmol/mg protein. The half-saturation and half-degradation periods for the ligand-receptor complex were 15 and 10 s, respectively. The specific binding sites from glioblastoma are similar to the peripheral-type receptors as their inhibition constant for Ro 5–4864 K i = 16 nM and that for clonazepam K i = 30 μM.