Characterisation of the binding of [3H]FR115427, a novel non-competitive NMDA receptor antagonist, to rat brain membranes.
The binding of [3H]FR115427 ([3H](+)-1-methyl-1-phenyl-1,2,3,4- tetrahydroisoquinoline) to rat cortical synaptosomal membranes was investigated. Binding was optimal at pH 7.4-8.0, and temperature had little effect on specific binding. Binding reached equilibrium within 30 min at 25 degrees C, and was reversible in the presence of excess unlabelled FR115427. [3H]FR115427 bound to a single population of non-interacting sites with an affinity of 45.4 +/- 3.9 nM, and a binding site density of 9.12 +/- 0.52 pmol/mg protein. The affinities of other N-methyl-D-aspartate (NMDA) receptor channel blockers for [3H]FR115427 binding sites were consistent with binding to a similar site to that occupied by dizocilpine. Binding was potentiated by L-glutamate and glycine with EC50 values of around 80 nM. In the presence of L-glutamate (10 microM), specific binding was increased 4-fold, whilst addition of glycine (10 microM) increased specific binding 2-fold. FR115427 exhibited marked stereoselectivity; (+)-FR115427 has 100-fold higher affinity than (-)-FR115427. This ligand may therefore be useful for the pharmacological investigation of the NMDA receptor ion channel.
Sherriffs
H J
HJ
Department of Pharmacology, University of Edinburgh, UK.
Shirakawa
K
K
Kelly
J S
JS
Olverman
H J
HJ
Kuno
A
A
Okubo
M
M
Butcher
S P
SP
D000818:Animals; D001921:Brain / Q000378:metabolism*; D016291:Dizocilpine Maleate / Q000031:analogs & derivatives / Q000494:pharmacology; D005971:Glutamates / Q000494:pharmacology; D005998:Glycine / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D007546:Isoquinolines / Q000493:pharmacokinetics* / Q000494:pharmacology; D008297:Male; D008566:Membranes / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors*; D013574:Synaptosomes / Q000187:drug effects / Q000378:metabolism; D044005:Tetrahydroisoquinolines
D005971:Glutamates; D007546:Isoquinolines; D016194:Receptors, N-Methyl-D-Aspartate; D044005:Tetrahydroisoquinolines; C084456:1-methyl-1-phenyl-1,2,3,4-tetrahydroisoquinoline; D016291:Dizocilpine Maleate; D005998:Glycine