Radioligand saturation binding experiments over large concentration ranges.

Receptor analysis using the radioligand binding saturation method in situations requiring a large concentration range of the ligand is theoretically straightforward but in practice can be relatively difficult. In this paper we review three approaches for carrying out such experiments and assess the strengths and weaknesses of each. The three are two saturation experiments, two homologous competition experiments, and the mixed homologous saturation experiment. The best approach depends upon the experimental conditions and constraints of the system studied, but in general the mixed homologous saturation experiment appears to be the most effective at minimizing the amount of radioligand needed while providing the greatest reliability in the results.