Specific binding of ( super(3)H)diazepam in mouse glioblastoma: The influence of clonazepam and Ro 5-4864 on ( super(3)H)diazepam binding

The reversible specific binding of ( super(3)H)diazepam was observed by a radioligand method in homogenates of cultured cells of mouse glioblastoma. It was characterized by an equilibrium dissociation constant K sub(d) + 91 plus or minus 5 nM and the number of maximal binding sites (B sub(max)) of of 1006 plus or minus 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 sub(i) = 16 nM and that for clonazepam K sub(i) = 30 mu M.