Presence of peripheral benzodiazepine binding sites on primary rat skeletal fibroblasts

Employing [3H]Ro5-4864 as a radioligand, the existence of peripheral benzodiazepine binding sites in rat hind limb skeletal fibroblasts was explored. Saturable, high affinity binding of this ligand is described for fibroblasts and cell membrane preparations, demonstrating a pharmacological profile characteristic for such receptors. The binding of [3H]Ro5-4864 exhibited higher affinity and density in fibroblasts compared to membrane preparations. A quaternaryamine derivative of PK 11195 showed a similar potency as a displacer of [3H]Ro5-4864 in both preparations. The data suggest that peripheral benzodiazepine receptors are present in the plasma membrane of primary mammalian fibroblasts.