The pharmacological characterization of 5-HT3 receptor binding sites in rabbit ileum: Comparison with those in rat ileum and rat brain

Abstract

We have further characterized the 5-HT3 receptors in rat and rabbit tissues by evaluating the binding of the 5-HT3 receptor ligand, [3H]GR67330 to homogenates of rabbit ileum, rat ileum and rat brain (entorhinal cortex). In each tissue specific [3H]GR67330 binding represented a single saturable, high affinity site (Kd = 0.14, 0.18, 0.076 nM in rabbit ileum, rat ileum and rat brain respectively). The densities of sites present in rabbit and rat ileum were similar to that present in rat brain (Bmax = 63, 47, 72 fmol/mg protein in rabbit ileum, rat ileum and rat brain respectively). In each tissue, 5-HT3 receptor agonists and antagonists potently competed for [3H]GR67330 binding. Derived inhibi..