Calcium signalling in secretory cells.
Stimulation of secretory cells with muscarinic agonists leads to an increase in the intracellular Ca (2+)concentration ([Ca (2+)]( i)), which activates protein secretion through exocytosis and causes closure of gap junctions between adjacent cells. In addition, the increase in [Ca (2+)](i) activates three different kinds of ion channels: large K(+) channels, Cl(-) channels and non-specific cation channels. The opening of those channels leads to an increase of [Na(+ )] and a decrease of [Cl(-)] and [K(+) ] in the cell. The two components that contribute to the increase in [Ca (2+)]( i) are calcium release from intracellular stores, localised in the endoplasmic reticulum and calcium influx through the plasma membrane. Several models for the regulation of [Ca (2+)](i) have been proposed, including a recently suggested model whereby a distinct pathway involving arachidonic acid is added to the well-established capacitative model. Different hypotheses concerning coupling between the intra-cellular calcium stores and membrane channels co-exist. In addition to a historical overview, recent developments and future challenges are discussed in this review.
University of Twente, the Netherlands l.a.c.kallenberg@student.utwente.nl
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Kallenberg
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism; D002412:Cations; D002462:Cell Membrane / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism; D005089:Exocytosis; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism; D008954:Models, Biological; D011188:Potassium / Q000378:metabolism; D015221:Potassium Channels / Q000378:metabolism; D015398:Signal Transduction; D012964:Sodium / Q000378:metabolism
D015220:Calcium Channels; D002412:Cations; D015221:Potassium Channels; D015544:Inositol 1,4,5-Trisphosphate; D012964:Sodium; D011188:Potassium; D002118:Calcium