TY - JOUR
T1 - 3H-catecholamine binding to α-receptors in rat brain
T2 - Enhancement by reserpine
AU - U'Prichard, David C.
AU - Snyder, Solomon H.
N1 - Funding Information:
We thank Mrs. Linda Hester and Mr. Peter Sheehan for their excellent technical assistance, and Miss Pamela Morgan for manuscript preparation. This research was supported by USPHS grant MH-18501 to S.H.S., USPHS fellowship award MH--5105 to D.C.U'P., and by grants from the McKnight and John A. Hartford Foundation, Inc.
PY - 1978/9/15
Y1 - 1978/9/15
N2 - (±)-3H-Epinephrine and (-)-3H-norepinephrine bind to rat cortex membranes in a saturable manner with dissociation constants of 16.7 and 27 nM0 respectively. The maximum number f 3H-catecholamine binding sites, 10-12 pmoles/g tissue, and the pharmacological characteristics of (±)-3H-epinephrine binding, indicate that the catecholamines label the same α-noradrenergic receptor in the rat as does 3H-clonidine. At 25°, (±)-3H-epinephrine binding associates rapidly to equilibrium, and dissociates in a biphasic manner. The affinities of α-agonists at the 3H-catecholamine binding site are 2-4 fold weaker in the rat than in the calf cortex under the same experimental conditions. Ergot alkaloids and phenoxybenzamine have similar affinities in the two tissues, whereas phentolamine and WB-4101 are 8-10 times weaker in the rat. Reserpine (0.25 mg/kg s.c. per day for 3 weeks) causes 25 and 46% increases in the numbers of (±)-3H-epinephrine and 3H-WB-4101 α-receptor binding sites respectively, and a 51% increase in the number of 3H-dihydroalprenolol β-receptor sites, in rat forebrain. Reserpine pretreatment does not alter the affinities of either α-or β-receptor 3H-ligands.
AB - (±)-3H-Epinephrine and (-)-3H-norepinephrine bind to rat cortex membranes in a saturable manner with dissociation constants of 16.7 and 27 nM0 respectively. The maximum number f 3H-catecholamine binding sites, 10-12 pmoles/g tissue, and the pharmacological characteristics of (±)-3H-epinephrine binding, indicate that the catecholamines label the same α-noradrenergic receptor in the rat as does 3H-clonidine. At 25°, (±)-3H-epinephrine binding associates rapidly to equilibrium, and dissociates in a biphasic manner. The affinities of α-agonists at the 3H-catecholamine binding site are 2-4 fold weaker in the rat than in the calf cortex under the same experimental conditions. Ergot alkaloids and phenoxybenzamine have similar affinities in the two tissues, whereas phentolamine and WB-4101 are 8-10 times weaker in the rat. Reserpine (0.25 mg/kg s.c. per day for 3 weeks) causes 25 and 46% increases in the numbers of (±)-3H-epinephrine and 3H-WB-4101 α-receptor binding sites respectively, and a 51% increase in the number of 3H-dihydroalprenolol β-receptor sites, in rat forebrain. Reserpine pretreatment does not alter the affinities of either α-or β-receptor 3H-ligands.
KW - Adrenoceptor binding
KW - Catecholamines
KW - Rat brain
KW - Reserpine
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U2 - 10.1016/0014-2999(78)90339-4
DO - 10.1016/0014-2999(78)90339-4
M3 - Article
C2 - 212279
AN - SCOPUS:0018198380
SN - 0014-2999
VL - 51
SP - 145
EP - 155
JO - European Journal of Pharmacology
JF - European Journal of Pharmacology
IS - 2
ER -