Calcium signaling and secretion in pituitary cells.
An important trigger of hormone secretion from pituitary cells is a rise in cytosolic Ca(2+) ([Ca(2+)](i)). Pituitary cells may modulate [Ca(2+)](i) by an increased membrane flux from the extracellular space and/or by a release from intracellular stores. Both mechanisms can support exocytosis, although in different pituitary cell types one or the other mechanism may predominate. Molecular events transducing a rise in [Ca(2+)](i) into hormone secretion are still poorly understood. Here, the exocytotic machinery in pituitary cells is briefly reviewed in terms of the spatial organization of [Ca(2+)](i) elevation relative to the Ca(2+) sensor(s).
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Robert Zorec is at the Laboratory of Neuroendocrinology, Institute of Pathophysiology, School of Medicine, University of Ljubljana, 1105 Ljubljana, Slovenia.