Tuesday, August 4, 2009

Regulation of exocytosis via release of Ca2+ from intracellular stores

Author's Abstract: COPYRIGHT 1999, John Wiley & Sons, Inc. The release of Ca(super 2+) from intracellular stores is an important trigger for secretion in many sell types. Depending on the spatial relationship between the intracellular Ca(super 2+) stores and the site of exocytosis, the Ca(super 2+) signal can be very local or spread throughout the entire cell. Here, we review how the release of Ca(super 2+) from inositol trisphospate (IP(sub 3))-sensitive stores contributes differently to the stimulus-secretion coupling in three types of secretory cells (acinar cells of the pancrease, gonadotrophs, and corticotrophs of the anterior pituitary gland). We propose that in both pancreatic acinar cells and pituitary gonadotrophs the IP(sub 3)-sensitive stores may be in close proximity to the sites of exocytosis such that the concentration of Ca(super 2+) at those sites are transiently much higher than the average cytosolic (Ca(sub 2+) concentration. In contract, the local Ca(super 2+) gradient is less prominent in pituitary corticotrophs. Finally, some recent technical developments that may contribute significantly to future investigations of local Ca(super 2+) signals are discussed.

author: Tse, Frederick W., Tse, Amy

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