Evaluation of the alpha-adrenoceptor antagonistic action of berberine in isolated organs.
The selectivity and specificity of berberine (CAS 2086-83-1) for alpha-adrenoceptor subtypes have been studied. alpha 1-Adrenoceptors were investigated in rat and rabbit aorta and alpha 2-adrenoceptors in guinea-pig ileum preparations. Subtype selectivity was then assessed by calculating the selectivity ratios from Ke (equilibrium constant) values. Berberine was found to be more potent for the postsynaptic alpha 1-adrenoceptors than presynaptic alpha 2-adrenoceptors. The selectivity ratios were 1.9 and 3.1 for rabbit and rat aorta, respectively. In the rabbit aorta, responses to norepinephrine and phenylephrine were both inhibited by berberine with lower affinity than that in the rat aorta. The pA2 values for berberine obtained from the norepinephrine and phenylephrine experiments were also found significantly different in rat aorta. However, similar pA2 values were found in rabbit aorta for those agonists.
Department of Pharmacology, Faculty of Medicine, Hacettepe University, Ankara, Turkey.
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Olmez
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Ilhan
D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology*; D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects; D001599:Berberine / Q000494:pharmacology*; D003000:Clonidine / Q000037:antagonists & inhibitors; D005260:Female; D006168:Guinea Pigs; D007082:Ileum / Q000187:drug effects; D066298:In Vitro Techniques; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000187:drug effects; D009638:Norepinephrine / Q000037:antagonists & inhibitors; D010656:Phenylephrine / Q000037:antagonists & inhibitors; D011817:Rabbits; D051381:Rats
D000317:Adrenergic alpha-Antagonists; D001599:Berberine; D010656:Phenylephrine; D003000:Clonidine; D009638:Norepinephrine