Tritium labelling of two highly selective agonists for CCK-B receptor: [3H]propionyl-Tyr(SO3Na)-gNle-mGly-Trp-(N-Me)Nle-Asp-Phe-NH2([3H]pBC 264) [3H]propionyl-γDLys-Trp-Nle-Asp-Phe-NH2([3H]pBC 254)
✍ Scribed by P. J. Corringer; C. Durieux; M. Ruiz-Gayo; B. P. Roques
- Publisher
- John Wiley and Sons
- Year
- 1992
- Tongue
- French
- Weight
- 415 KB
- Volume
- 31
- Category
- Article
- ISSN
- 0022-2135
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✦ Synopsis
Abstract
Among the CCK‐B receptor agonists reported to date, the two modified peptides BC 264 and BC 254 display a high affinity and selectivity for this binding site and are highly protected from enzymatic degradation. Recently, we reported the biological properties of a tritiated analog of this agonist, [^3^H]pBC 264, which fullfils all the criteria required for in vitro as well as in vivo studies of the CCK‐B receptor. On the other hand, BC 254 displays a high affinity for the CCK‐B binding sites in the guinea‐pig (K~1~= 0.56 nM) while its affinity in the rat is more than 60‐fold lower, a difference which could be due to the occurrence of CCK‐B receptor subtypes. In the present paper, we report the synthesis of [^3^H]pBC 264 and of the new tritiated ligand [^3^H]pBC 254 using [^3^H] NPS (N‐succinimidyl[2,3‐^3^H]propionate) as labelling agent. These two probes have high specific activity (70–100 Ci/mmol) and will enable extensive studies of the CCK‐B receptors to be carried out.