Antagonism by reactive blue 2 but not by brilliant blue G of extracellular ATP-evoked responses in PC12 phaeochromocytoma cells.
1. The effects of reactive blue 2 and brilliant blue G, which have been shown to block extracellular ATP-evoked responses, were investigated to discover whether these compounds act as P2-purinoceptor antagonists in PC12 phaeochromocytoma cells. 2. Reactive blue 2 (10 to 100 microM) suppressed the ATP-stimulated dopamine secretion from PC12 cells in a dose-dependent manner. The concentration-response curve for ATP was shifted to the right and the maximal response was decreased by reactive blue (30 and 100 microM). Brilliant blue G (up to 100 microM) did not significantly affect the secretion. 3. Reactive blue 2 (10 to 100 microM) suppressed the ATP-activated inward current recorded from the voltage-clamped cells in a concentration-dependent manner. Brilliant blue G (up to 100 microM) did not affect the current. 4. The results suggest that reactive blue 2 but not brilliant blue G is a P2-purinoceptor antagonist in PC12 cells. The purinoceptors in these cells may be the same type as those involved in ATP-evoked smooth muscle relaxation, judging from the antagonism by reactive blue 2.
Inoue
K
K
Division of Pharmacology, National Institute of Hygienic Sciences, Tokyo, Japan.
Nakazawa
K
K
Ohara-Imaizumi
M
M
Obama
T
T
Fujimori
K
K
Takanaka
A
A
D000255:Adenosine Triphosphate / Q000037:antagonists & inhibitors*; D000310:Adrenal Gland Neoplasms / Q000503:physiopathology*; D001557:Benzenesulfonates / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism; D002395:Catecholamines / Q000378:metabolism; D004298:Dopamine / Q000378:metabolism; D004594:Electrophysiology; D008564:Membrane Potentials / Q000187:drug effects; D010673:Pheochromocytoma / Q000503:physiopathology*; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology*; D011983:Receptors, Purinergic / Q000187:drug effects; D014227:Triazines / Q000494:pharmacology*; D014407:Tumor Cells, Cultured / Q000187:drug effects*
D001557:Benzenesulfonates; D002395:Catecholamines; D011500:Protein Synthesis Inhibitors; D011983:Receptors, Purinergic; D014227:Triazines; C012842:Cibacron Blue F 3GA; D000255:Adenosine Triphosphate; C006796:brilliant blue; D002118:Calcium; D004298:Dopamine