Intracellular Ca^<2+> Increase in Neuro-2A Cells and Rat Astrocytes Following Stimulation of Bradykinin B_2 Receptor

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Murine neuroblastoma cell line Neuro−2A cells and rat brain astrocytes showed a dose−dependent increase in intracellular Ca2+ in response to bradykinin, when assessed by a single cell image analyzing system.The Ca2+ increase in Neuro−2A cells by bradykinin was also examined by a suspension fluorescent assay using fura−2 loading.The Ca2+ increase in both cases was suppressed by a bradykinin B2 receptor antagonist, Hoe 140, but not by a B1 receptor antagonist, des−Arg−Hoe 140, suggesting that the effect occurred via specific B2 receptor activation.RT−PCR for bradykinin B2 receptor mRNA showed that both Neuro−2A cells and the astrocytes expressed B2 receptor mRNA.Binding of [3H]bradykinin to Neuro−2A cells was assessed, and a specific binding constant of 0.75 nM was determined.Furthermore, the increase in [Ca2+]i by bradykinin could be caused by a release of Ca2+ from storage sites in the endoplasmic reticulum, since thapsigargin and U−73122 attenuated the effect of bradykinin in Neuro−2A as well as in astrocytes.These results indicate that both astrocytes and neuroblastoma Neuro−2A cells stimulated by bradykinin could express a bradykinin B2 receptor−mediated intracellular Ca2+ increase leading to signal transduction.
社団法人日本薬理学会の論文
2000-10-01