Migita Keisuke, Zhao Yumei, Katsuragi Takeshi
Department of Pharmacology, School of Medicine, Fukuoka University, Fukuoka, Japan.
Biochem Pharmacol. 2007 May 15;73(10):1676-82. doi: 10.1016/j.bcp.2007.01.021. Epub 2007 Jan 20.
We previously found that adenosine stimulates ATP release from Madin-Darby canine kidney (MDCK) cells, by activating an Ins(1,4,5)P(3) sensitive-calcium (Ca(2+)) pathway through the stimulation of A(1) receptors. Thus, we investigated the intracellular pathway of ATP efflux after the rise in intracellular Ca(2+) in MDCK cells. Adenosine evoked an increase in mitochondrial Ca(2+) using Rhod-2/AM, a mitochondrial Ca(2+) indicator. Adenosine-induced ATP release was inhibited by mitochondrial modulators, such as oxidative phosphorylation modulators (carbonyl cyanide 3-chlorophenylhydrazone and oligomycin), mitochondrial ADP/ATP carrier inhibitors (N-ethylmaleimide, carboxyatractyloside and bongkrekic acid), a mitochondrial Na(+)-Ca(2+) exchange inhibitor (CGP-37157). In addition, mitochondrial modulators significantly reduced intracellular ATP content. On the other hand, 2-deoxy-glucose (2-DG) induced a greater decrease in intracellular ATP content than mitochondrial modulators. ATP release was still induced by adenosine in the presence of 5mM 2-DG. These results suggest that mitochondria play an important role in the signaling pathway of adenosine-triggered ATP release in MDCK cells.
我们先前发现，腺苷通过刺激A(1)受体激活Ins(1,4,5)P(3)敏感的钙（Ca(2+)）途径，从而刺激马-达二氏犬肾（MDCK）细胞释放ATP。因此，我们研究了MDCK细胞内Ca(2+)升高后ATP流出的细胞内途径。使用线粒体Ca(2+)指示剂Rhod-2/AM，腺苷可引起线粒体Ca(2+)增加。腺苷诱导的ATP释放受到线粒体调节剂的抑制，如氧化磷酸化调节剂（羰基氰3-氯苯腙和寡霉素）、线粒体ADP/ATP载体抑制剂（N-乙基马来酰亚胺、羧基苍术苷和硼酸）、线粒体Na(+)-Ca(2+)交换抑制剂（CGP-3715）。此外，线粒体调节剂显著降低细胞内ATP含量。另一方面，2-脱氧葡萄糖（2-DG）比线粒体调节剂引起细胞内ATP含量更大程度的降低。在5mM 2-DG存在的情况下，腺苷仍可诱导ATP释放。这些结果表明，线粒体在MDCK细胞中腺苷触发的ATP释放信号通路中起重要作用。
