Goldman S J, Dickinson E S, Slakey L L
J Cyclic Nucleotide Protein Phosphor Res. 1983;9(1):69-78.
Both endothelial and smooth muscle cells cultured from swine aorta responded to adenosine by elevating cAMP levels. cAMP was found both intracellularly and released into the incubation medium. Total cAMP in endothelial cells in buffer alone was 2 pmol cAMP/10(6) cells. Total cAMP reached a maximum stimulated level of 2 times control at 640 microM adenosine. The level of cAMP in unstimulated smooth muscle cells was 7 pmol/10(6) cells. Total cAMP was increased 2-fold at 10 microM adenosine and reached a maximum stimulated level of as much as 20 times control at 640 microM adenosine. Kinetics of release of cAMP from smooth muscle cells show that fractional release rates were increased 2 to 7 fold by 10 microM adenosine and 7 to 29 fold by 160 microM adenosine. These experiments indicate that adenosine specifically stimulates release of cAMP as well as synthesis. The phosphodiesterase inhibitor 3-isobutyl-l-methylxanthine (IBMX) had complex effects on the distribution of cAMP between the cells and medium. The data are consistent with the model that IBMX is a low affinity competitive inhibitor of adenosine, and is itself slightly effective as an agonist for release.
从猪主动脉培养的内皮细胞和平滑肌细胞对腺苷的反应都是通过提高环磷酸腺苷（cAMP）水平。在内皮细胞内和释放到培养液中的cAMP都被检测到。仅在缓冲液中的内皮细胞内的总cAMP为2皮摩尔cAMP/10⁶个细胞。在640微摩尔腺苷作用下，总cAMP达到最大刺激水平，为对照的2倍。未受刺激的平滑肌细胞中的cAMP水平为7皮摩尔/10⁶个细胞。在10微摩尔腺苷作用下，总cAMP增加了2倍，在640微摩尔腺苷作用下达到最大刺激水平，高达对照的20倍。平滑肌细胞释放cAMP的动力学表明，10微摩尔腺苷使释放分数率增加了2至7倍，160微摩尔腺苷使其增加了7至29倍。这些实验表明，腺苷特异性地刺激cAMP的释放以及合成。磷酸二酯酶抑制剂3 -异丁基-1 -甲基黄嘌呤（IBMX）对细胞和培养基之间cAMP的分布有复杂的影响。这些数据与IBMX是腺苷的低亲和力竞争性抑制剂且其本身作为释放激动剂有轻微作用的模型一致。
