adopted in using radioligands to enable tracing it’s binding to receptors. A good example of a radioligand binding experiment using the recent availability of a whole range of potent and selective prostaglandin agonists and antagonists is determining the pharmacology of [3H]Prostaglandin E1/[3H]Prostaglandin E2 and [3H]Prostaglandin F2 Binding to EP3 and FP Prostaglandin Receptor Binding Sites in Bovine Corpus Luteum.The procedure carried out involved grinding brain BCLM homogenates, centrifuging and placing in an incubator. After this the [3H]PGE1 and [3H]PGE2 binding assay was carried out. Then the same method was carried out using [3H]PGF2 binding assay. These were then mounted onto slides then autoradiographed.The study demonstrated the presence of high affinity and specific binding sites for [3H]PGE1, [3H]PGE2 and [3H]PGF2 in washed total particulate BCLM homogenates. Scatchard analyses indicated that [3H]PGE1 and [3H]PGE2 bound to a single population of nanomolar affinity receptor sites (fig 7a,7b). Both [3H]PGE1 and [3H]PGE2 labelled the same population of EP- receptor sites in the tissue because Kd and Bmax values obtained for both radioligands were very similar. (fig 7a,7b).The pharmacological specificity of both radioligands in the BCLM was essentially identical (Fig 8c). [3H]PGF2 labelled a high affinity (nM Kd) and an apparent low affinity (M Kd) site in the washed BCLM homogenates as determined from several experiments (Fig 7c). The major aim of this study was to define the PG receptor subtypes binding sites present in the BCLM using the latest pharmacological tools. Current studies have demonstrated that both [3H]PGE2 and [3H]PGE1 selectively label EP3 receptors in the BCLM due to potent highly selective EP3-receptor prostaglandins, such as GR-63799,SC-46275, sulprostone and enprostil competing for specific [3H]PGE2 and [3H]PGE1 binding with nanomolar affinities, while prostaglandins...
