SPATIAL DOMAINS OF CA2-CELLS( SIGNALING IN SECRETORY EPITHELIAL)

Secretory epithelial cells are found in exocrine organs such as the pa ncreas and are also found in the lining of the lungs and gut. One impo rtant regulator of cell function in epithelial cells is the concentrat ion of cytosolic Ca2+. The study of Ca2+ signaling in these cells has a long history and recent work has now identified, at the molecular le vel, key components in the Ca2+ signaling cascade. Furthermore, advanc es in fluorescent imaging techniques has enabled a detailed insight in to the subcellular distribution of the agonist-evoked [Ca2+](i) signal . A number of spatially different [Ca2+](i) responses have been identi fied. Firstly, global [Ca2+](i) signals are observed in response to hi gh agonist concentrations. Secondly, at lower agonist concentrations t rains of local [Ca2+](i) spikes, restricted to the secretory pole regi on of pancreatic acinar cells, have been identified. Finally, these lo cal [Ca2+](i) spikes have now been further devolved into microdomains of [Ca2+](i) elevation. The [Ca2+](i) signal within a single microdoma in has been shown to be the crucial trigger in the regulation of the i on channels important in fluid secretion.