Document Detail

Identification of the alpha1L-adrenoceptor in rat cerebral cortex and possible relationship between alpha1L- and alpha1A-adrenoceptors.
MedLine Citation:
PMID:  18223667     Owner:  NLM     Status:  MEDLINE    
BACKGROUND AND PURPOSE: In addition to alpha1A, alpha1B and alpha1D-adrenoceptors (ARs), putative alpha1L-ARs with a low affinity for prazosin have been proposed. The purpose of the present study was to identify the alpha1A-AR and clarify its pharmacological profile using a radioligand binding assay.
EXPERIMENTAL APPROACH: Binding experiments with [3H]-silodosin and [3H]-prazosin were performed in intact tissue segments and crude membrane preparations of rat cerebral cortex. Intact tissue binding assays were also conducted in rat tail artery.
KEY RESULTS: [3H]-silodosin at subnanomolar concentrations specifically bound to intact tissue segments and membrane preparations of rat cerebral cortex at the same density (approximately 150 fmol mg(-1) total tissue protein). The binding sites in intact segments consisted of alpha1A and alpha1L-ARs that had different affinities for prazosin, while the binding sites in membranes showed an alpha1A-AR-like profile having single high affinity for prazosin. [3H]-prazosin also bound at subnanomolar concentrations to alpha1A and alpha1B-ARs but not alpha1L-ARs in cerebral cortex; the binding densities being approximately 200 and 290 fmol mg(-1) protein in the segments and the membranes, respectively. In the segments of tail artery, [3H]-silodosin only recognized alpha1A-ARs, whereas [3H]-prazosin bound to alpha1A and alpha1B-ARs.
CONCLUSIONS AND IMPLICATIONS: The present study clearly reveals the presence of alpha1L-ARs as a pharmacologically distinct entity from alpha1A and alpha1B-ARs in intact tissue segments of rat cerebral cortex but not tail artery. However, the alpha1L-ARs disappeared after tissue homogenization, suggesting their decomposition and/or their pharmacological profile changes to that of alpha1A-ARs.
S Morishima; F Suzuki; H Yoshiki; A S Md Anisuzzaman; Z S Sathi; T Tanaka; I Muramatsu
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2008-01-28
Journal Detail:
Title:  British journal of pharmacology     Volume:  153     ISSN:  0007-1188     ISO Abbreviation:  Br. J. Pharmacol.     Publication Date:  2008 Apr 
Date Detail:
Created Date:  2008-04-01     Completed Date:  2008-06-23     Revised Date:  2013-06-06    
Medline Journal Info:
Nlm Unique ID:  7502536     Medline TA:  Br J Pharmacol     Country:  England    
Other Details:
Languages:  eng     Pagination:  1485-94     Citation Subset:  IM    
Division of Pharmacology, Department of Biochemistry and Bioinformative Sciences, School of Medicine, University of Fukui, Eiheiji, Fukui, Japan.
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MeSH Terms
Adrenergic alpha-1 Receptor Antagonists
Adrenergic alpha-Antagonists / pharmacology
Arteries / metabolism
Binding Sites
Cerebral Cortex / metabolism
Indoles / pharmacology
Prazosin / pharmacology
Radioligand Assay
Rats, Wistar
Receptors, Adrenergic, alpha-1 / metabolism*
Tail / blood supply
Reg. No./Substance:
0/Adra1a protein, rat; 0/Adra1b protein, rat; 0/Adrenergic alpha-1 Receptor Antagonists; 0/Adrenergic alpha-Antagonists; 0/Indoles; 0/Receptors, Adrenergic, alpha-1; 19216-56-9/Prazosin; CUZ39LUY82/silodosin

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