[3H] 8 ‐Cyclopentyl‐1,3 ‐dipropylxanthine Binding to A1 Adenosine Receptors of Intact Rat Ventricular Myocytes
[3H] 8 ‐Cyclopentyl‐1,3 ‐dipropylxanthine Binding to A1 Adenosine Receptors of Intact Rat Ventricular Myocytes
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[3H] 8-环戊基-1,3-二丙基黄嘌呤与完整大鼠心室肌细胞 A1 腺苷受体的结合
DOI：
10.1161/01.res.63.3.613
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发表时间：
1988
影响因子：
20.1
通讯作者：
U. Schwabe
中科院分区：
文献类型：
--
作者：
Dirk Martens;M. Lohse;U. Schwabe
本研究的目的是在完整的大鼠心室肌细胞，这被认为是介导腺苷的负性肌力作用的腺苷受体的鉴定。以腺苷受体拮抗剂[3 H]-8-环戊基-1，3-二丙基黄嘌呤为放射性配体。放射性配体与完整肌细胞的结合是快速、可逆和可饱和的，结合能力为每个细胞40，000个结合位点。放射性配体的解离常数为0.48 nM。腺苷受体拮抗剂8-环戊基-1，3-二丙基黄嘌呤，“黄嘌呤胺同源物”和茶碱是竞争性抑制剂，其亲和力与其他组织中A1受体的结果一致。使用腺苷受体激动剂R-N6-苯基异丙基腺苷、5 '-N-乙基甲酰氨基腺苷和S-N6-苯基异丙基腺苷的竞争实验给出了单相位移曲线，K1值为50 nM、440 nM和4，300 nM，这与心脏膜中GTP诱导的低亲和力状态非常一致。对激动剂的低亲和力不是由于激动剂诱导的脱敏，而是与异丙肾上腺素抑制环腺苷酸积累的相应ICM 50值密切相关。有人建议，只有一个低亲和力状态的A1受体可以检测到在完整的大鼠心肌细胞中，由于在完整的细胞中存在高浓度的鸟嘌呤核苷酸。
The purpose of the present study was the identification of A, adenosine receptors in intact rat ventricular myocytes, which are thought to mediate the negative inotropic effects of adenosine. The adenosine receptor antagonist [3H]-8-cydopentyl-1,3-dipropylxanthine was used as radioligand. Binding of the radioligand to intact myocytes was rapid, reversible, and saturable with a binding capacity of 40,000 binding sites per cell. The dissociation constant of the radioligand was 0.48 nM. The adenosine receptor antagonists 8-cyclopentyl-1,3-dipropylxanthine, “xanthine amine congener,” and theophyUine were competitive inhibitors with affinities in agreement with results obtained for A1 receptors in other tissues. Competition experiments using the adenosine receptor agonists R-N6-phenylisopropyladenosine, 5'-N-ethylcarboxamidoadenosine, and S-N6-phenylisopropyladenosine gave monophasic displacement curves with K1 values of 50 nM, 440 nM, and 4,300 nM, which agreed well with the GTP-inducable low affinity state in cardiac membranes. The low affinity for agonists was not due to agonist-induced desensitization, and correlated well with the corresponding ICM50 values for the inhibition of cyclic AMP accumulation by isoprenaline. It is suggested that only a low affinity state of A1 receptors can be detected in intact rat myocytes due to the presence of high concentrations of guanine nucleotides in intact cells.
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DOI：
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发表时间：
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期刊：
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影响因子：
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DOI：
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期刊：
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影响因子：
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