Characterization of flunitrazepam and beta-carboline high affinity binding in bovine pineal gland

High affinity binding of3H-fiunitrazepam (FNZP) to crude membrane preparations of bovine pineal membranes was examined by a rapid filtration procedure through Whatman GFB paper. At 0 °C binding reached equilibrium in about 20 min. Scatchard analysis of data at equilibrium revealed a single populatio...

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Detalles Bibliográficos
Autores principales: Lowenstein, P.R., Cardinali, D.P.
Formato: JOUR
Materias:
Barbiturates
Benzodiazepine binding
GABA
Pineal gland
β-Carboline binding
4 aminobutyric acid
4' chlorodiazepam
barbituric acid derivative
benzodiazepine
clonazepam
flumazenil
flunitrazepam
pentobarbital
radioisotope
animal cell
beta carboline 3 carboxylic acid ethyl ester h 3
cattle
cell membrane
central nervous system
drug receptor binding
endocrine system
flunitrazepam h 3
nonhuman
pharmacokinetics
pineal body
Animal
Anti-Anxiety Agents, Benzodiazepine
Benzodiazepines
Binding Sites
Carbolines
Cattle
Comparative Study
Flunitrazepam
gamma-Aminobutyric Acid
In Vitro
Indoles
Kinetics
Pentobarbital
Pineal Gland
Rats
Species Specificity
Support, Non-U.S. Gov't
Acceso en línea:http://hdl.handle.net/20.500.12110/paper_00283835_v37_n2_p150_Lowenstein
Aporte de:
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
Descripción
Sumario:High affinity binding of3H-fiunitrazepam (FNZP) to crude membrane preparations of bovine pineal membranes was examined by a rapid filtration procedure through Whatman GFB paper. At 0 °C binding reached equilibrium in about 20 min. Scatchard analysis of data at equilibrium revealed a single population of binding sites with dissociation constant (K<inf>d</inf>) = 3.14 ± 0.45 nM and binding site concentration (B<inf>max</inf>) = 55.6 ± 5.6 fmol/mg protein. Kinetic analysis of the association and dissociation curves indicated a kinetic K<inf>d</inf> = 1.13 nM, in reasonable agreement to that obtained at equilibrium. When various benzodiazepine (BZP) analogues were tested for their ability to inhibit3H-FNZP binding, the following K<inf>i</inf>(nM) were obtained: Clonazepam (0.22), Ro 15-1788(0.48), FNZP (0.95), Ro 5-4864 (> 10,000). When the β-carboline derivative3H-ethyl-β-carboline-3-carboxylate ester (EβCEE) was used as a radioligand, K<inf>d</inf> at equilibrium (0.98 nM), kinetic K<inf>d</inf> (1.69 n M) and affinity order for analogues were in close agreement to those found for FNZP binding; however, B<inf>max</inf> was about 60% that observed for3H-FNZP binding. Addition of GABA or pentobarbital (100 μM) to pineal membranes increased3H-FNZP binding by 55 and 72%. These results suggest the existence of a mixed population of type 1 and type 2 central BZP receptor subclass in bovine pineal gland. © 1983 S. Karger AG, Basel.

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