title: High-affinity binding sites for PK 11195, but not for RO5-4864, in porcine aortic smooth muscle.
abstract: Peripheral benzodiazepine (BZ) binding sites were characterized in porcine aortic smooth muscle membrane preparation. [3H]PK11195 bound with high affinity to the membranes (Kd = 8.6 + 0.9 nM), whereas [3H]Ro5-4864 bound slightly to the membranes. The Ki value of Ro5-4864 obtained from the inhibition of [3H]PK 11195 binding was 1200 + 200 nM, which was 480 times weaker than that obtained in rat kidney. Furthermore, the Ro5-4864 effect was temperature-insensitive. When [3H]PK 11195 binding was examined in porcine, human and rat platelets, Ro5-4864 inhibited the binding in porcine and human platelets one order of magnitude less potently than that in rat platelets. These results suggest that low affinity for Ro5-4864 in porcine aorta smooth muscle originates in porcine tissue, but not in smooth muscle.
authors.affiliation: Shionogi Research Laboratories, Shionogi & Co. Ltd., Osaka, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Mihara
authors.forename: M
authors.initials: M
authors.lastname: Fujimoto
mesh_terms: D000818:Animals; D001011:Aorta / Q000378:metabolism; D001570:Benzodiazepinones / Q000493:pharmacokinetics* / Q000494:pharmacology; D001665:Binding Sites; D003080:Cold Temperature; D004305:Dose-Response Relationship, Drug; D007546:Isoquinolines / Q000493:pharmacokinetics* / Q000494:pharmacology; D007668:Kidney / Q000187:drug effects; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D013552:Swine; D013696:Temperature; D013997:Time Factors
chemical_list: D001570:Benzodiazepinones; D007546:Isoquinolines; C028513:4'-chlorodiazepam; C037850:PK 11195