Jacobson K A, Guay-Broder C, van Galen P J, Gallo-Rodriguez C, Melman N, Jacobson M A, Eidelman O, Pollard H B
Molecular Recognition Section, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA.
Biochemistry. 1995 Jul 18;34(28):9088-94. doi: 10.1021/bi00028a018.
A series of 8-substituted derivatives of 1,3,7-alkylxanthines was synthesized as potential activators of chloride efflux from a human epithelial cell line (CFPAC) expressing the cystic fibrosis transmembrane regulator (CFTR) delta F508 mutation. Their interactions with rat brain A1 and A2a receptors were also studied in radioligand binding experiments. Substitution was varied at the xanthine 1-, 3-, 7- and 8-positions. 1,3-Dipropyl-8-cyclopentylxanthine (CPX) stimulated Cl- efflux in the 10(-8) M range, with a maximal effect reaching 200% of control and diminishing at higher concentrations. The potent adenosine antagonist 8-[4-[[[[(2-aminoethyl)amino]carbonyl]methyl]oxy]phenyl]- 1,3-dipropylxanthine, nonselective at human A1 and A2a receptors, was inactive in Cl- efflux. 1,3-Diallyl-8-cyclohexylxanthine (DAX) was highly efficacious in stimulating chloride efflux with levels reaching > 300% of control, although micromolar concentrations were required. 1,3,7-Trimethyl-8-(3-chlorostyryl)xanthine, an A2a-selective adenosine antagonist, was only weakly active. Caffeine, which acts as an nonselective adenosine antagonist in the range of 10(-5) M, was active in Cl- efflux in the low nanomolar range but with low efficacy. Thus, among the xanthine derivatives of diverse structure, there was no correlation between potency in Cl- efflux and adenosine antagonism. Poly(A)+ RNA isolated from CFPAC-1 cells showed no hybridization to a human A1 receptor cDNA probe, excluding this receptor as a mediator of CPX-elicited Cl- efflux. Thus, this action of xanthines in stimulating Cl- efflux in CFPAC cells, which express a defective CFTR, represents a novel site of action apparently unrelated to adenosine receptors.
合成了一系列1,3,7 - 烷基黄嘌呤的8 - 取代衍生物，作为表达囊性纤维化跨膜调节因子（CFTR）ΔF508突变的人上皮细胞系（CFPAC）中氯离子外流的潜在激活剂。还通过放射性配体结合实验研究了它们与大鼠脑A1和A2a受体的相互作用。黄嘌呤的1 -、3 -、7 - 和8 - 位取代情况各不相同。1,3 - 二丙基 - 8 - 环戊基黄嘌呤（CPX）在10^(-8) M范围内刺激氯离子外流，最大效应达到对照的200%，且在更高浓度时减弱。强效腺苷拮抗剂8 - [4 - [[[[(2 - 氨基乙基)氨基]羰基]甲基]氧基]苯基] - 1,3 - 二丙基黄嘌呤，对人A1和A2a受体无选择性，在氯离子外流实验中无活性。1,3 - 二烯丙基 - 8 - 环己基黄嘌呤（DAX）在刺激氯离子外流方面非常有效，水平达到对照的300%以上，尽管需要微摩尔浓度。1,3,7 - 三甲基 - 8 - (3 - 氯苯乙烯基)黄嘌呤，一种A2a选择性腺苷拮抗剂，活性较弱。咖啡因在10^(-5) M范围内作为非选择性腺苷拮抗剂，在低纳摩尔范围内对氯离子外流有活性，但效力较低。因此，在结构多样的黄嘌呤衍生物中，氯离子外流效力与腺苷拮抗作用之间没有相关性。从CFPAC - 1细胞中分离的聚腺苷酸（Poly(A)+）RNA与人A1受体cDNA探针无杂交信号，排除了该受体作为CPX引发氯离子外流的介导因子。因此，黄嘌呤在表达缺陷CFTR的CFPAC细胞中刺激氯离子外流的这种作用，代表了一个明显与腺苷受体无关的新作用位点。
