Agonist-induced changes in [Ca2+]i in N1E-115 cells: differential effects of bradykinin and carbachol

The addition of bradykinin to populations of fura-2 loaded N1E-115 neuroblastoma cells produced an increase in intracellular calcium which rapidly reached a peak and returned to baseline within 60 s. The response was concentration dependent and unaffected by removal of extracellular calcium or addition of the inorganic channel blocker Ni2+. Similar transient responses were seen with histamine and angiotensin II and experiments monitoring manganese entry suggest that agonist responses in this cell line involve mainly release of calcium from intracellular stores. However, unlike bradykinin, the response to carbachol, at all concentrations, failed to return completely to baseline suggesting a small secondary influx component and highlighting possible differences between the mechanisms of calcium elevation by these two agonists.