Extracellular adenosine 5'-triphosphate-evoked norepinephrine secretion not relating to voltage-gated Ca channels in pheochromocytoma PC12 cells.
Characteristics of extracellular ATP-stimulated norepinephrine (NE) secretion were investigated by the batch method in relation to membrane current measured with the whole cell voltage-clamp technique. Extracellular ATP stimulated [3H]NE secretion from PC12 cells in a concentration range from 10 microM to 1 mM. The maximal effect of ATP was about 5 times larger than that of nicotine. ATP-stimulated secretion was extracellular Ca-dependent, but it was not inhibited by the Ca-channel blockers, cadmium (300 microM) or nicardipine (10 microM). Extracellular ATP activated an inward current in PC12 cells and the peak amplitude of the current was about 5 times larger than that activated by nicotine. These findings suggest that extracellular ATP activates receptor-operated channels and causes NE secretion.
Inoue
K
K
Division of Pharmacology, National Institute of Hygienic Sciences, Tokyo, Japan.
Nakazawa
K
K
Fujimori
K
K
Takanaka
A
A
D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000502:physiology; D015220:Calcium Channels / Q000502:physiology*; D008564:Membrane Potentials / Q000187:drug effects; D009638:Norepinephrine / Q000378:metabolism / Q000493:pharmacokinetics*; D010673:Pheochromocytoma; D051381:Rats; D014407:Tumor Cells, Cultured / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology
D015220:Calcium Channels; D000255:Adenosine Triphosphate; D002118:Calcium; D009638:Norepinephrine