An Intracellular Calcium Oscillations Model Including Mitochondrial Calcium Cycling

Calcium is a ubiquitous second messenger. Mitochondria contributes significantly to intracellular Ca²⁺ dynamics. The experiment of Kaftan et al. J. Biol. Chem. 275(2000) 25465 demonstrated that inhibiting mitochondrial Ca²⁺ uptake can reduce the frequency of cytosolic Ca²⁺ concentration oscillations of gonadotropes. By considering the mitochondrial Ca²⁺ cycling we develop a three-variable model of intracellular Ca²⁺oscillations based on the models of Atri et al. Biophys. J. 65 (1993) 1727 and Falcke et al. Biophys. J. 77 (1999) 37. The model reproduces the fact that mitochondrial Ca²⁺ cycling increases the frequency of cytosolic Ca²⁺ oscillations, which accords with Kaftan's results. Moreover the model predicts that when the mitochondria overload with Ca²⁺, the cytosolic Ca²⁺ oscillations vanish, which may trigger apoptosis.