A Biophysically Based Mathematical Model for the Kinetics of Mitochondrial Na+-Ca^sup 2+^ Antiporter

Sodium-calcium antiporter is the primary efflux pathway for ... in respiring mitochondria, and hence plays an important role in mitochondrial ... homeostasis. Although experimental data on the kinetics of ...-... antiporter are available, the structure and composition of its functional unit and kinetic mechanisms associated with the ...-... exchange (including the stoichiometry) remains unclear. To gain a quantitative understanding of mitochondrial ... homeostasis, a biophysical model of ...-... antiporter is introduced that is thermodynamically balanced and satisfactorily describes a number of independent data sets under a variety of experimental conditions. The model is based on a multistate catalytic binding mechanism for carrier-mediated facilitated transport and Eyring's free energy barrier theory for interconversion and electrodiffusion. The model predicts the activating effect of membrane potential on the antiporter function for a ...:... electrogenic exchange as well as the inhibitory effects of both high and low pH seen experimentally. The model is useful for further development of mechanistic integrated models of mitochondrial ... handling and bioenergetics to understand the mechanisms by which ... plays a role in mitochondrial signaling pathways and energy metabolism. (ProQuest: ... denotes formulae/symbols omitted.)