In:
Journal of Cerebral Blood Flow & Metabolism, SAGE Publications, Vol. 14, No. 3 ( 1994-05), p. 453-465
Abstract:
In vivo benzodiazepine receptor equilibrium dissociation constant, K D , and maximum number of binding sites, B max , were measured by single photon emission computerized tomography (SPECT) in three baboons. Animals were injected with a bolus followed by a constant i.v. infusion of the high affinity benzodiazepine ligand [ 123 I]iomazenil. Plasma steady-state concentration and receptor–ligand equilibrium were reached within 2 and 3 h, respectively, and were sustained for the duration (4–9 h) of the experiments (n = 15). At the end of the experiments, a receptor saturating dose of flumazenil (0.2 mg/kg) was injected to measure nondisplaceable activity. Experiments were carried out at various levels of specific activity, and Scatchard analysis was performed for derivation of the K D (0.59 ± 0.09 n M) and B max (from 126 n M in the occipital region to 68 n M in the striatum). Two animals were killed and [ 125 I]iomazenil B max and K D were measured at 22 and 37°C on occipital homogenate membranes. In vitro values of B max (114 ± 33 n M) and 37°C K D (0.66 ± 0.16 n M) were in good agreement with in vivo values measured by SPECT. This study demonstrates that SPECT can be used to quantify central neuroreceptors density and affinity.
Type of Medium:
Online Resource
ISSN:
0271-678X
,
1559-7016
DOI:
10.1038/jcbfm.1994.56
Language:
English
Publisher:
SAGE Publications
Publication Date:
1994
detail.hit.zdb_id:
2039456-1
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