Abstract
[3H]Clonidine (26.7 Ci/mmole) binds with high affinity to sites on rat brain membranes with properties of alpha-noradrenergic receptors. [3H]Clonidine binding shows a biphasic pattern in kinetic and saturation experiments. Fifty percent of the specific binding of 0.4 nM [3H]clonidine is dissociated rapidly in 2 min by excess norepinephrine or clonidine, and the remaining 50% disssociates at a 10-fold slower rate. When slowly-dissociating [3H]clonidine binding is examined in isolation, saturation curves show a single population of high-affinity sites with a K(D) of 0.5 nM and B(max) of 1.3-1.6 pmoles/g tissue in cerebral cortex. Rapidly-dissociating [3H]clonidine binding, estimated from the difference between total binding and high-affinity binding, involves a single population of lower affinity sites with a K(D) of 3.0 nM and B(max) of 9-10 pmoles/g cerebral cortex tissue. Alpha agonists are in general more potent at the high affinity [3H]clonidine site, while alpha antagonists are more potent at the low affinity site. α-Methylnorepinephrine is less potent than norepinephrine at the high affinity site, but more potent at the low affinity site. Neither [3H]-clonidine binding site resembles the alpha receptor site labeled by [3H]WB-4101. The distribution of high and low affinity [3H]clonidine binding throughout rat central nervous system is different. High affinity binding levels vary 14 fold between lowest values in corpus striatum and cerebellum, and highest values in cerebral cortex. Low affinity binding varies less regionally, with highest levels in hypothalamus. 6-Hydroxydopamine treatment doubles the number of high affinity [3H]clonidine sites in the cortex, but does not alter the number of low affinity sites. 6-Hydroxydopamine increases high affinity binding much more than low affinity binding throughout the brain. 6-Hydroxydopamine also increases by 50% the number of [3H]WB-4101 and [3H]epinephrine alpha receptor sites in the cerebral cortex.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 47-60 |
| Number of pages | 14 |
| Journal | Molecular Pharmacology |
| Volume | 16 |
| Issue number | 1 |
| State | Published - 1979 |
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ASJC Scopus subject areas
- Pharmacology
Cite this
Multiple apparent alpha-noradrenergic receptor binding sites in rat brain : Effect of 6-hydroxydopamine. / U'Prichard, D. C.; Bechtel, W. D.; Rouot, B. M.; Snyder, Solomon H.
In: Molecular Pharmacology, Vol. 16, No. 1, 1979, p. 47-60.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Multiple apparent alpha-noradrenergic receptor binding sites in rat brain
T2 - Effect of 6-hydroxydopamine
AU - U'Prichard, D. C.
AU - Bechtel, W. D.
AU - Rouot, B. M.
AU - Snyder, Solomon H
PY - 1979
Y1 - 1979
N2 - [3H]Clonidine (26.7 Ci/mmole) binds with high affinity to sites on rat brain membranes with properties of alpha-noradrenergic receptors. [3H]Clonidine binding shows a biphasic pattern in kinetic and saturation experiments. Fifty percent of the specific binding of 0.4 nM [3H]clonidine is dissociated rapidly in 2 min by excess norepinephrine or clonidine, and the remaining 50% disssociates at a 10-fold slower rate. When slowly-dissociating [3H]clonidine binding is examined in isolation, saturation curves show a single population of high-affinity sites with a K(D) of 0.5 nM and B(max) of 1.3-1.6 pmoles/g tissue in cerebral cortex. Rapidly-dissociating [3H]clonidine binding, estimated from the difference between total binding and high-affinity binding, involves a single population of lower affinity sites with a K(D) of 3.0 nM and B(max) of 9-10 pmoles/g cerebral cortex tissue. Alpha agonists are in general more potent at the high affinity [3H]clonidine site, while alpha antagonists are more potent at the low affinity site. α-Methylnorepinephrine is less potent than norepinephrine at the high affinity site, but more potent at the low affinity site. Neither [3H]-clonidine binding site resembles the alpha receptor site labeled by [3H]WB-4101. The distribution of high and low affinity [3H]clonidine binding throughout rat central nervous system is different. High affinity binding levels vary 14 fold between lowest values in corpus striatum and cerebellum, and highest values in cerebral cortex. Low affinity binding varies less regionally, with highest levels in hypothalamus. 6-Hydroxydopamine treatment doubles the number of high affinity [3H]clonidine sites in the cortex, but does not alter the number of low affinity sites. 6-Hydroxydopamine increases high affinity binding much more than low affinity binding throughout the brain. 6-Hydroxydopamine also increases by 50% the number of [3H]WB-4101 and [3H]epinephrine alpha receptor sites in the cerebral cortex.
AB - [3H]Clonidine (26.7 Ci/mmole) binds with high affinity to sites on rat brain membranes with properties of alpha-noradrenergic receptors. [3H]Clonidine binding shows a biphasic pattern in kinetic and saturation experiments. Fifty percent of the specific binding of 0.4 nM [3H]clonidine is dissociated rapidly in 2 min by excess norepinephrine or clonidine, and the remaining 50% disssociates at a 10-fold slower rate. When slowly-dissociating [3H]clonidine binding is examined in isolation, saturation curves show a single population of high-affinity sites with a K(D) of 0.5 nM and B(max) of 1.3-1.6 pmoles/g tissue in cerebral cortex. Rapidly-dissociating [3H]clonidine binding, estimated from the difference between total binding and high-affinity binding, involves a single population of lower affinity sites with a K(D) of 3.0 nM and B(max) of 9-10 pmoles/g cerebral cortex tissue. Alpha agonists are in general more potent at the high affinity [3H]clonidine site, while alpha antagonists are more potent at the low affinity site. α-Methylnorepinephrine is less potent than norepinephrine at the high affinity site, but more potent at the low affinity site. Neither [3H]-clonidine binding site resembles the alpha receptor site labeled by [3H]WB-4101. The distribution of high and low affinity [3H]clonidine binding throughout rat central nervous system is different. High affinity binding levels vary 14 fold between lowest values in corpus striatum and cerebellum, and highest values in cerebral cortex. Low affinity binding varies less regionally, with highest levels in hypothalamus. 6-Hydroxydopamine treatment doubles the number of high affinity [3H]clonidine sites in the cortex, but does not alter the number of low affinity sites. 6-Hydroxydopamine increases high affinity binding much more than low affinity binding throughout the brain. 6-Hydroxydopamine also increases by 50% the number of [3H]WB-4101 and [3H]epinephrine alpha receptor sites in the cerebral cortex.
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M3 - Article
VL - 16
SP - 47
EP - 60
JO - Molecular Pharmacology
JF - Molecular Pharmacology
SN - 0026-895X
IS - 1
ER -