ISSN:
1432-1912
Schlagwort(e):
Stereoisomers
;
Enantiomers
;
Imidazolines
;
Rat
;
pithed
;
Adrenoceptors
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Medizin
Notizen:
Summary Adrenoceptor-mediated effects of the enantiomers of the optically active imidazoline, 2-(3,4,α-trihydroxybenzyl)imidazoline, and the corresponding desoxy derivative, 2-(3,4-dihydroxybenzyl)imidazoline, have been investigated in the pithed rat. The enantiomers and desoxy derivative were potent pressor agents with a direct action mediated predominantly via postsynaptic vascular α2-adrenoceptor. These compounds were significantly less potent at presynaptic α2-adrenoceptor in rat heart. The rank order of potency for the two enantiomers and desoxy derivative at postsynaptic vascular α1- and presynaptic cardiac α2-adrenoceptor in pithed rat were: desoxy≥R(−) 〉(+), consistent with our previous findings in vitro. This order of potency is not in agreement with the rank order of R(−)〉S(+)=desoxy which is predicted by the Easson-Stedman Hypothesis. The β-adrenoceptor-mediated chronotropic and β-adrenoceptor-mediated vasodepressor effects of these imidazolines were also investigated in pithed rat and found to be weaker than either the α1- or α2-adrenoceptor-mediated effects. However, the rank order of potency of the enantiomers and corresponding desoxy derivative for β1- and β2-adrenoceptor-mediated effects was found to be similar to that order predicted by the Easson-Stedman Hypothesis. Studies with these optically active imidazoline enantiomers and corresponding desoxy derivativative indicate that quantitative as well as qualitative differences exist in the stereochemical requirements of α- and β-adrenoceptor. The results also support our previous observations which suggest that phenethylamines and imidazolines may interact differently with α-adrenoceptor since the former adhere strictly to the Easson-Stedman Hypothesis whereas the latter do not.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/BF00497667
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