ISSN:
1432-1912
Keywords:
Key wordsα1-adrenoceptor subtypes
;
Urethra
;
Cloned receptor
;
NS-49
;
Binding assay
;
Correlation
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstract To identify the α1-adrenoceptor subtypes in the human prostatic urethra, we compared the potencies of various α1-adrenoceptor agonists and antagonists in inhibiting [3H]tamsulosin binding to human prostatic urethral membranes with their potencies in inhibiting the binding of (+)-β-([125I]iodo-4-hydroxyphenyl)ethylaminomethyl-tetralone ([125I]HEAT) to cloned human α1a, α1b and α1d subtypes. The α1A-selective antagonists 5-methylurapidil and (+)niguldipine showed higher affinities for both cloned α1a and urethral α1-adrenoceptors than for cloned α1b- and α1d-adrenoceptors. NS-49, (R)-3′-(2-amino-1-hydroxyethyl)-4′-fluoromethanesulfonanilide hydrochloride, recently characterized as an α1A-selective agonist, also showed high affinity for the cloned α1a subtype and urethral α1-adrenoceptors. Prazosin showed lower affinity for α1-adrenoceptors in the human prostatic urethra than for any of the three cloned α1-adrenoceptors. Comparison of the affinities of α1-adrenoceptor agonists and antagonists for human prostatic urethral α1-adrenoceptors to their affinities for the three cloned α1 subtypes indicated a close correlation between the affinities for human urethral α1 and the cloned α1a-adrenoceptors. However, prazosin did not conform to this pattern. These findings suggest that the predominant α1-adrenoceptor in the human urethra is the α1A subtype, and that an α1L subtype which has been characterised by its low affinity for prazosin, may also be present.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/PL00004962
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