[125I]Aminobenzyladenosine, a new radioligand with improved specific binding to adenosine receptors in heart.
[125I]Aminobenzyladenosine, a new radioligand with improved specific binding to adenosine receptors in heart.
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[125I]氨基苄基腺苷，一种新的放射性配体，具有改善的与心脏中腺苷受体的特异性结合。
DOI：
10.1161/01.res.56.2.279
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发表时间：
1985
影响因子：
20.1
通讯作者：
Sadek,S
中科院分区：
文献类型：
--
作者：
Linden,J;Patel,A;Sadek,S
大鼠心脏膜上腺苷受体的密度比大鼠脑膜上的受体密度低25倍。因此，对脑有用的腺苷放射性配基，如L-[~3H]苯基异丙基腺苷、[~3H]环己基腺苷、[~3H]-2-氯腺苷和L-[125I]羟基苯基异丙基腺苷，由于非特异性结合与特异性结合的比率很高，对心脏的作用有限。我们合成了一种新的放射性配基[125I]-N6-4-氨基苯基腺苷，它与大鼠心肌细胞膜的非特异性结合是其他放射性配基的六分之一。[125I]-N6-4-氨基苯基腺苷与大鼠脑室膜结合，其解离常数相当于L-[125I]羟基苯基异丙基腺苷，Bmax为15.2fmol/mg蛋白。[125I]-N6-4-氨基苯基腺苷与脑膜的亲和力(Kd=1.93 nM)高于与心膜的亲和力(Kd=11.6 nM)。在放射性配基Kd处，结合到心肌膜上的[125I]-N6-4-氨基苯基腺苷总量的60%是特异结合的。碘化氨基苄基腺苷使其与腺苷受体的亲和力增加了22倍，这可能是由于碘的位阻或疏水效应。这种新的配体被发现是一种完全的腺苷激动剂，因为它能够抑制腺苷在分离的鸡胚胎心脏细胞和大鼠脂肪细胞中的循环积累。[125I]-N6-4-氨基苯基腺苷结合到一个单一的亲和部位，并被其他腺苷类似物从心脏和脑内的腺苷受体上取代，其效力顺序为L-苯基异丙基腺苷大于5‘-乙基甲酰胺腺苷。这些特征表明放射性配基与Ri腺苷受体结合。
The density of adenosine receptors in membranes derived from rat hearts in 25 times lower than the density of receptors in rat brain membranes. Consequently, adenosine radioligands which are useful in brain such as l-[3H]phenylisopropyladenosine, [3H]cyclohexyladenosine, [3H]-2-chloroadenosine and l-[125I]hydroxyphenylisopropyladenosine are of limited usefulness in heart, due to a high ratio of nonspecific to specific binding. We have synthesized a new radioligand, [125I]-N6-4-aminobenzyladenosine, which binds to rat heart membranes with one-sixth the nonspecific binding of the other radioligands. [125I]-N6-4-aminobenzyladenosine bound to rat ventricle membranes with a KD equivalent to that of l-[125I]hydroxyphenylisopropyladenosine and a Bmax of 15.2 fmol/mg protein. [125I]-N6-4-aminobenzyladenosine bound with a higher affinity to brain (KD = 1.93 nM) than to heart membranes (KD = 11.6 nM). At the radioligand KD, 60% of the total [125I]-N6-4-aminobenzyladenosine bound to heart membranes was specifically bound. Iodination of aminobenzyladenosine increased its affinity for the adenosine receptor by 22-fold, possibly due to a steric or hydrophobic effect of iodine. The new ligand was found to be a full adenosine agonist based on its ability to inhibit cyclic adenosinemonophosphate accumulation in isolated embryonic chick heart cells and rat adipocytes. [125I]-N6-4-Aminobenzyladenosine bound to a single affinity site and was displaced from cardiac and brain adenosine receptors by other adenosine analogues with a potency order of l-phenylisopropyladenosine greater than 5'-N-ethylcarboxamide adenosine. These characteristics suggest that the radioligand binds to an Ri adenosine receptor.