Ohigashi T, Nakashima J, Aggarwal S, Brookins J, Agrawal K, Fisher J W
Department of Pharmacology, Tulane University School of Medicine, New Orleans, LA 70112, USA.
J Lab Clin Med. 1995 Sep;126(3):299-306.
The purpose of this study was to characterize the effects of two new adenosine A2 agonists, 2-(p-(2-carboxyethyl)phenethyl amino)-5'-N-ethylcarboxamidoadenosine (CGS-21680) and N6-(2(3,5-dimethoxyphenyl)-2-(2-methylphenyl)ethyl)-adenosine (DPMA), on erythropoietin (EPO) production in vivo and in vitro. Intravenous injections of CGS-21680 (100 to 500 nmol/kg mouse/day) and DPMA (50 to 500 nmol/kg mouse/day) for 4 days produced significant increases in serum levels of EPO in exhypoxic polycythemic mice. CGS-21680 (10(-7) to 10(-6) mol/L) and DPMA (10(-8) to 10(-5) mol/L) also produced significant increases in medium levels of EPO in a cloned EPO-producing Hep3B hepatocellular carcinoma cell line after 18 hours of incubation in 1% O2. Both compounds also increased cellular cAMP levels significantly in a dose-dependent manner after 1 hour of incubation. A2 receptor binding assays with tritiated CGS-21680 revealed a single type of adenosine receptor binding site on Hep3B cell membranes with a dissociation constant of 132.9 nmol/L and a binding capacity of 270.6 fmol/mg protein. The Ki competition binding values versus tritiated CGS-21680 were 217 nmol/L for CGS-21680 and 86.8 nmol/L for DPMA. These results indicate that adenosine A2 receptor activation amplifies EPO production in response to hypoxia, both in vivo and in vitro.
本研究的目的是表征两种新型腺苷A2激动剂，即2-(对-(2-羧乙基)苯乙氨基)-5'-N-乙基甲酰胺基腺苷（CGS-21680）和N6-(2-(3,5-二甲氧基苯基)-2-(2-甲基苯基)乙基)-腺苷（DPMA），对体内和体外促红细胞生成素（EPO）产生的影响。对低氧性红细胞增多症小鼠静脉注射CGS-21680（100至500 nmol/kg小鼠/天）和DPMA（50至500 nmol/kg小鼠/天），持续4天，可使血清EPO水平显著升高。在1%氧气中孵育18小时后，CGS-21680（10^(-7)至10^(-6) mol/L）和DPMA（10^(-8)至10^(-5) mol/L）也可使克隆的产生EPO的Hep3B肝癌细胞系培养基中的EPO水平显著升高。孵育1小时后，两种化合物均以剂量依赖性方式显著提高细胞内cAMP水平。用氚标记的CGS-21680进行的A2受体结合试验显示，Hep3B细胞膜上存在单一类型的腺苷受体结合位点，解离常数为132.9 nmol/L，结合容量为270.6 fmol/mg蛋白质。与氚标记的CGS-21680相比，CGS-21680的Ki竞争结合值为217 nmol/L，DPMA的Ki竞争结合值为86.8 nmol/L。这些结果表明，腺苷A2受体激活可增强体内和体外低氧时EPO的产生。
