Effects of anions on ATP-induced [Ca2+], increase in NG108-15 cells.
We investigated the effects of anions on different P2 receptors by measuring ATP-induced increase in intracellular Ca2+ concentration ([Ca2+]i) in fura-2-loaded NG108-15 and PC12 cells. In NG108-15 cells, ATP at 100 microM and 1 mM induced a transient and a sustained [Ca2+]i increase, respectively. The former, but not the latter, was inhibited by U-73122, indicating that the former was via the P2Y2 receptor and the latter via the P2X7 receptor. When external Cl- was replaced by other anions, the [Ca2+]i increase mediated by the P2Y2 receptor was not changed, but that mediated by the P2X7 receptor varied in the order of aspartate- > methanesulfonate > Cl- > Br > or = I-. In PC12 cells, transient [Ca2+]i increases mediated by the P2Y2 and P2X2 receptors were not affected by various anions. These results suggest that modulation by anions is unique to the P2X7 receptor and does not occur in P2Y2 and P2X2 receptors. This may be because the mechanism of ATP binding to the P2X7 receptor may be different than that to other P2 receptors.
Department of Pharmacology, Fukushima Medical University, School of Medicine, Hikarigaoka, Japan.
Tomokazu
T
Watano
Isao
I
Matsuoka
Kohei
K
Ogawa
Junko
J
Kimura
D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000818:Animals; D000838:Anions / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D004963:Estrenes / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D051379:Mice; D016716:PC12 Cells; D058910:Purinergic P2 Receptor Agonists; D058919:Purinergic P2 Receptor Antagonists; D011760:Pyrrolidinones / Q000494:pharmacology; D051381:Rats; D018048:Receptors, Purinergic P2 / Q000502:physiology; D058486:Receptors, Purinergic P2X7; D014407:Tumor Cells, Cultured
D000838:Anions; D004963:Estrenes; C546469:P2rx7 protein, mouse; D058910:Purinergic P2 Receptor Agonists; D058919:Purinergic P2 Receptor Antagonists; D011760:Pyrrolidinones; D018048:Receptors, Purinergic P2; D058486:Receptors, Purinergic P2X7; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; D000255:Adenosine Triphosphate; D002118:Calcium