RT info:eu-repo/semantics/article T1 Cytosolic organelles shape calcium signals and exo–endocytotic responses of chromaffin cells A1 García García, Antonio A1 Padín, Fernando A1 Fernández Morales, Jose Carlos A1 Maroto, Marcos A1 García-Sancho Martín, Francisco Javier K1 Calcio K1 Bioquímica AB The concept of stimulus–secretion coupling was born from experiments performed in chromaffin cells 50years ago. Stimulation of these cells with acetylcholine enhances calcium (Ca2+) entry and this generates atransient elevation of the cytosolic Ca2+ concentration ([Ca2+]c) that triggers the exocytotic release of catecholamines.The control of the [Ca2+]c signal is complex and depends on various classes of plasmalemmalcalcium channels, cytosolic calcium buffers, the uptake and release of Ca2+ from cytoplasmic organelles,such as the endoplasmic reticulum, mitochondria, chromaffin vesicles and the nucleus, and Ca2+ extrusionmechanisms, such as the plasma membrane Ca2+-stimulated ATPase, and the Na+/Ca2+ exchanger.Computation of the rates of Ca2+ fluxes between the different cell compartments support the proposalthat the chromaffin cell has developed functional calcium tetrads formed by calcium channels, cytosoliccalcium buffers, the endoplasmic reticulum, and mitochondria nearby the exocytotic plasmalemmal sites.These tetrads shape the Ca2+ transients occurring during cell activation to regulate early and late steps ofexocytosis, and the ensuing endocytotic responses. The different patterns of catecholamine secretion inresponse to stress may thus depend on such local [Ca2+]c transients occurring at different cell compartments,and generated by redistribution and release of Ca2+ by cytoplasmic organelles. In this manner,the calcium tetrads serve to couple the variable energy demands due to exo–endocytotic activities withenergy production and protein synthesis. PB Elsevier SN 0143-4160 YR 2012 FD 2012 LK http://uvadoc.uva.es/handle/10324/6339 UL http://uvadoc.uva.es/handle/10324/6339 LA eng NO Cell Calcium, 2012, vol. 51, p. 309-320 NO Producción Científica DS UVaDOC RD 28-abr-2024