뱀장어 ( Anguilla japonica ) 장의 상피세포막에 존재하는 새로운 clonidine 결합 수용체에 관한 연구 = A New Receptor for site Clonidine in the Eel , Anguilla japonica Intestine

다국어 초록 (Multilingual Abstract)

A novel clonidine binding sites were characterized in the intestinal membrane isolated from seawater eels, Anguilla japonica. The specific clonidine binding sites consisted of at least two classes, high affinity (K_d =1.4 ± 0.3 nM n = 5) and low affinity (K_d = 175 ± 34 nM n = 5) sites. The specific binding of 2 nM [³H]clonidine was most enhanced at 20℃ and pH 7.5, and reversed by unlabelled clonidine. Such binding was hardly inhibited by adrenaline, yohimbine or rauwolscine, indicating that most binding sites are distinct from α₂-adrenoceptor. The specific clonidine binding sites was inhibited by various imidazoline/guanidinium drugs, indicating existence of imidazoline/guanidinium receptive sites (IGRS) or imidazoline receptors in the eel intestine. Competition experiments revealed that rank order to displace 2 nM [³H]clonidine from their binding sites was as follows : guanabenz ＞ cirazoline = naphazoline = UK14,304 = ST587 ≥ clonidine ≥ idazoxan = RX821002 = tolazoline ＞ ST93 = oxymetazoline = amiloride = ST91 ＞ yohimbine = efaroxan = rauwolscine ≥ adrenaline = ST567 = histamine = agmatine. Although physiological role of IGRS is not clear yet even in mammalian cell/tissues, eel intestine may be a good model to elucidate how the IGRS act in the cell and to decide what is the endogenous ligand for the IGRS.