Héron C, Billaud G, Costentin J, Bonnet J J
URA 1969, CNRS, UFR de Médecine et Pharmacle, Saint Etienne du Rouvray, France. p4
Eur J Pharmacol. 1996 Apr 22;301(1-3):195-202. doi: 10.1016/0014-2999(96)00050-7.
At 20 degrees C, [3H]GBR 12783, {1-[2-(diphenylmethoxy)ethyl]4-(3-phenyl-2-([1-3H]propenyl)-pip era zine} dissociated from the dopamine neuronal carrier present in rat striatal membranes with a t1/2 value of 27 min. At this temperature, KCI, CaCl2 and MgCl2 increased the binding dissociation, revealing that they recognize a binding site which is not mutually exclusive with that of [3H]GBR 12783. The comparison of the ability of KCl to increase the binding dissociation (by 160% at 30 mM KCl) with its potency as a binding inhibitor (Ki-2.6 +/- 0.3 mM) suggests an involvement of two recognition sites for K+ in binding inhibition, a not mutually exclusive site and another, mutually exclusive, site. Divalent cations mainly inhibited the binding via a mutually exclusive site since 3 mM Ca2+ and 10 mM Mg2+ increased the binding dissociation by 90% at 20 degrees C whereas their Ki values were 0.049 +/- 0.006 and 0.141 +/- 0.035 mM, respectively. Involvement of this mutually exclusive site was also supported by the persistence of the binding inhibition elicited by Ca2+ and Mg2+ at 0 degree C, a temperature at which they reduced the binding dissociation. At 20 degrees C, 100 mM NaCl did not modify [3H]GBR 12783 binding but it antagonized the binding dissociation elicited by inhibitory cations. Ca2+ reduced the off-rate of [3H]GBR 12783 binding at 0 degree C and in the presence of 100 mM Na+. Finally, [3H]GBR 12783-binding dissociation was increased by high 'cytosolic' K+ while 'synaptic' concentrations of Na+, K+, Ca2+, Mg2+ and Cl- were ineffective. A reduction of H2PO4-/HCO3- from 10 to 5 mM and a substitution of 5 mM H2PO4-/HCO3- by 5 mM Cl- increased the binding dissociation, suggesting that an anion-binding site could also regulate the binding.
在20摄氏度时，[3H]GBR 12783，即{1-[2-(二苯甲氧基)乙基]-4-(3-苯基-2-([1-3H]丙烯基)-哌嗪}从大鼠纹状体膜中的多巴胺神经元载体上解离，其半衰期值为27分钟。在此温度下，氯化钾、氯化钙和氯化镁增加了结合解离，表明它们识别的结合位点与[3H]GBR 12783的结合位点并非相互排斥。将氯化钾增加结合解离的能力（在30 mM氯化钾时增加160%）与其作为结合抑制剂的效力（Ki为2.6±0.3 mM）进行比较，表明在结合抑制中钾离子有两个识别位点参与，一个是非相互排斥的位点，另一个是相互排斥的位点。二价阳离子主要通过一个相互排斥的位点抑制结合，因为3 mM钙离子和10 mM镁离子在20摄氏度时使结合解离增加了90%，而它们的Ki值分别为0.049±0.006 mM和0.141±0.035 mM。钙离子和镁离子在0摄氏度时引起的结合抑制的持续性也支持了这个相互排斥位点的参与，在该温度下它们降低了结合解离。在20摄氏度时，100 mM氯化钠没有改变[3H]GBR 12783的结合，但它拮抗了抑制性阳离子引起的结合解离。钙离子在0摄氏度且存在100 mM钠离子的情况下降低了[3H]GBR 12783结合的解离速率。最后，高“胞质”钾离子增加了[3H]GBR 12783的结合解离，而“突触”浓度的钠离子、钾离子、钙离子、镁离子和氯离子则无效。将磷酸二氢根/碳酸氢根从10 mM降至5 mM以及用5 mM氯离子替代5 mM磷酸二氢根/碳酸氢根增加了结合解离，这表明一个阴离子结合位点也可能调节结合。
