Neuropeptide Y mobilizes intracellular Ca2+ and increases inositol phosphate production in human erythroleukemia cells |
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Authors: | A J Daniels E R Lazarowski J E Matthews E G Lapetina |
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Institution: | Medicinal Biochemistry Division, Wellcome Research Laboratories, Research Triangle Park, N.C. 27709. |
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Abstract: | The intracellular concentration of free Ca2+ was monitored by measuring the fluorescence of fura-2 loaded Human Erythroleukemia Cells. Neuropeptide Y (NPY) increased intracellular Ca2+ in a dose-dependent manner and the 50% effective concentration was 2 nM. Chelation of extracellular Ca2+ by EGTA did not reduce the NPY-mediated increase in cytoplasmic Ca2+, indicating that the increase in fluorescence was due to the release of intracellular Ca2+. A second dose of NPY, after intracellular Ca2+ had returned to basal levels, failed to elicit a response, indicating that the NPY receptor had undergone desensitization. In similar experiments, NPY increased the formation of inositol phosphates, suggesting that the mobilization of Ca2+ from intracellular stores in HEL cells was secondary to the generation of inositol phosphates and stimulation of phospholipase C. |
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