High affinity acceptor sites in guinea pig brain for [3H]52770 RP, a PAF antagonist

• Published in: Fundamental & clinical pharmacology Vol. 3; no. 1; p. 37
• Main Authors: Levy, C, Baudouy, N, Brun, V, Goze, O, Zundel, J L, Blanchard, J C, Laduron, P M
• Format: Journal Article
• Language: English
• Published: England 01.01.1989
• Subjects: Animals; Anti-Bacterial Agents; Antibiotics, Antitubercular - metabolism; Antibiotics, Antitubercular - pharmacokinetics; Brain - metabolism; Cations - pharmacology; Cerebral Cortex - metabolism; Guinea Pigs; In Vitro Techniques; Male; Membranes - metabolism; Peptides - metabolism; Peptides - pharmacokinetics; Platelet Activating Factor - antagonists & inhibitors; Proteins - metabolism; Receptors, Drug - metabolism; Stereoisomerism
• ISSN: 0767-3981
• DOI: 10.1111/j.1472-8206.1989.tb00028.x

[3H]52770 RP, a PAF antagonist, was found to bind with high affinity and in a reversible manner on specific and saturable binding sites in guinea pig cortical membranes. Scatchard analysis revealed the presence of one class of binding sites with an equilibrium dissociation constant of 0.38 nM and a Bmax of 1190 fmol/mg protein. However, these binding sites did not correspond to the PAF receptors described with this ligand in platelet plasma membranes; indeed, PAF and its analogs were unable to displace [3H]52770 RP binding in guinea pig brain. Therefore, one may conclude that [3H]52770 RP in guinea pig brain labels acceptor or recognition sites, rather than true receptor sites.