Inoue K, Watano T, Koizumi S, Nakazawa K, Burnstock G
Division of Pharmacology, National Institute of Health Sciences, Tokyo, Japan.
Eur J Pharmacol. 1994 Jul 15;268(2):223-9. doi: 10.1016/0922-4106(94)90192-9.
Effects of adenosine on inward current activated by extracellular ATP were examined in rat pheochromocytoma PC12 cells. Adenosine induced two types of modulation on the current activated by 30 microM ATP; a low concentration of adenosine (1 microM) inhibited the current whereas a high concentration (> 10 microM) enhanced the current. Neither the inhibition nor the enhancement was observed in cells pretreated with pertussis toxin (PTX), or in cells dialyzed with guanosine 5'-O-(2-thiotriphosphate) trilithium salt (GDP beta S). In contrast, dialysis with K-252a, a protein kinase inhibitor, abolished the inhibition, but not the enhancement. Adenosine induced similar inhibition and enhancement on ATP-evoked increase in intracellular free Ca2+ concentration. The results suggest that adenosine produces dual modulation on the ATP-activated channels through different mechanisms involving PTX-sensitive GTP-binding proteins.
在大鼠嗜铬细胞瘤PC12细胞中研究了腺苷对细胞外ATP激活的内向电流的影响。腺苷对30微摩尔ATP激活的电流产生两种类型的调节作用；低浓度腺苷（1微摩尔）抑制该电流，而高浓度（>10微摩尔）增强该电流。在用百日咳毒素（PTX）预处理的细胞中，或在用鸟苷5'-O-（2-硫代三磷酸）三锂盐（GDPβS）透析的细胞中，均未观察到抑制或增强作用。相反，用蛋白激酶抑制剂K-252a透析可消除抑制作用，但不能消除增强作用。腺苷对ATP诱发的细胞内游离Ca2+浓度升高产生类似的抑制和增强作用。结果表明，腺苷通过涉及PTX敏感的GTP结合蛋白的不同机制对ATP激活的通道产生双重调节作用。
