Cytoplasmic organelles determine complexity and specificity of calcium signalling in adrenal chromaffin cells.
Complex and coordinated fluctuations of intracellular free Ca2+ concentration ([Ca2+]c) regulate secretion of adrenaline from chromaffin cells. The physiologically relevant intracellular Ca2+ signals occur either as localized microdomains of high Ca2+ concentrations or as propagating Ca2+ waves, which give rise to global Ca2+ elevations. Intracellular organelles, the endoplasmic reticulum (ER), mitochondria and nuclear envelope, are endowed with powerful Ca2+ transport systems. Calcium uptake and Ca2+ release from these organelles determine the spatial and temporal parameters of Ca2+ signalling events. Furthermore, the ER and mitochondria form close relations with the sites of plasmalemmal Ca2+ entry, creating 'Ca2+ signalling triads' which act as elementary operational units, which regulate exocytosis. Ca2+ ions accumulating in the ER and mitochondria integrate exocytotic activity with energy production and protein synthesis.
García-Sancho
J
J
Departamento de Fisiología, Facultad de Medicina, Instituto de Biología y Genética Molecular, Universidad de Valladolid y Consejo Superior de Investigaciones Científicas, Valladolid, Spain. jgsancho@ibgm.uva.es
Verkhratsky
A
A
D000818:Animals; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling; D019439:Chromaffin Cells / Q000378:metabolism* / Q000648:ultrastructure; D003593:Cytoplasm / Q000378:metabolism*; D004837:Epinephrine / Q000378:metabolism; D005089:Exocytosis; D006706:Homeostasis; D006801:Humans; D015388:Organelles / Q000378:metabolism*
D002118:Calcium; D004837:Epinephrine