BINDING OF THE BENZODIAZEPINE LIGAND [3H]-RO 15-1788 TO MEMBRANE PREPARATIONS OF THE RABBIT AND TURTLE RETINA

1. We have studied the binding of [H-3]-RO 15-1788 to membrane preparations of the retina of rabbit (Lepus cunicula) and turtle (Pseudemys scripta elegans). 2. In both species, [H-3]-RO 15-1788 binding was maximal at 0-degree-C and decreased with increasing temperature. It was saturable, protein concentration-dependent and specific. Flunitrazepam, unlabelled RO 15-1788 and ethyl-beta-carboline were the most effective displacers, whereas RO 5,4864 was ineffective. 3. In both turtle and rabbit retina, Scatchard analysis indicated the presence of a single binding site for [H-3]-RO 15-1788. The K(D) was 0.75 nM in both turtle and rabbit, while the B(max) were 520 and 250 fmol/mg protein in turtle and rabbit respectively. A study of the association rate of [H-3]-RO 15-1788 binding revealed faster kinetics in turtle, as compared to rabbit.