Mitochondria as regulators of stimulus-evoked calcium signals in neurons

An important challenge in the study of Ca2+ signalling is to understand the dynamics of intracellular Ca2+ levels during and after physiological stimu lation. While extensive information is available regarding the structural a nd biophysical properties of Ca2+ channels, pumps and exchangers that contr ol cellular Ca2+ movements, little is known about the quantitative properti es of the transporters that are expressed together in intact cells or about the way they operate as a system to orchestrate stimulus-induced Ca2+ sign als. This lack of information is particularly striking given that many qual itative properties of Ca2+ signals (e.g. whether the Ca2+ concentration wit hin a particular organelle rises or falls during stimulation) depend critic ally on quantitative properties of the underlying Ca2+ transporters (e.g. t he rates of Ca2+ uptake and release by the organelle). This monograph descr ibes the in situ characterization of Ca2+ transport pathways in sympathetic neurons, showing how mitochondrial Ca2+ uptake and release systems define the direction and rate of net Ca2+ transport by this organelle, and how the interplay between mitochondrial Ca2+ transport and Ca2+ transport across t he plasma membrane contribute to depolarization-evoked Ca2+ signals in inta ct cells. (C) 2000 Harcourt Publishers Ltd.