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Flunitrazepam Binding to Intact and Homogenized Astrocytes and Neurons in Primary Cultures
Author(s) -
Bender Alexander S.,
Hertz Leif
Publication year - 1984
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1984.tb05389.x
Subject(s) - flunitrazepam , homogenization (climate) , population , diazepam , astrocyte , biophysics , chemistry , benzodiazepine , biology , microbiology and biotechnology , biochemistry , endocrinology , pharmacology , receptor , medicine , central nervous system , biodiversity , ecology , environmental health
[ 3 H]Flunitrazepam binds to intact and homogenized mouse astrocytes and neurons in primary cultures. In intact cells, the binding is to a single, high‐affinity, saturable population of benzodiazepine binding sites with a K D of 7 n M and B max of 6,033 fmol/mg protein in astrocytic cells and a K D of 5 nM and B max of 924 fmol/mg protein in neurons. After homogenization, the B max values decrease drastically in both cell types, but most in astrocytes. The temperature and time dependency are different for the two cell types, with a faster association and dissociation in astrocytes than in neurons and a greater temperature sensitivity in the astrocytes. Moreover, flunitrazepam binding sites on neuronal and astrocytic cells have different pharmacological profiles. In intact astrocytic cells, Ro 5–4864 ( K 1 = 4 n M ) is the most potent displacing compound, followed by diazepam ( K 1 = 6 n M ) and clonazepam ( K 1 = 600 n M ). In intact neurons, the relative order of potency of these three compounds is different: diazepam ( K 1 = 7 n M ) is the most potent, followed by clonazepam ( K 1 = 26 n M ) and Ro 5–4864, which has little effect. After homogenization the potency of diazepam decreases. We conclude that both neuronal and astrocytic cells possess high‐affinity [ 3 H]flunitrazepam binding sites. The pharmacological profile and kinetic characteristics differ between the two cell types and are further altered by homogenization.