Mitochondrial energetics, pH regulation, and ion dynamics: a computational-experimental approach

Area of Science:

• Mitochondrial physiology and bioenergetics
• Computational biology and mathematical modeling

Background:

• Mitochondrial energetics involve complex interactions of ion gradients, pH, and substrate metabolism.
• Previous models often simplified these dynamics, limiting their predictive power for physiological and pathological states.

Purpose of the Study:

• To develop an integrated computational model of mitochondrial energetics.
• To incorporate calcium (Ca2+), proton (H+), sodium (Na+), and phosphate dynamics.
• To validate the model against experimental data from guinea pig mitochondria.

Main Methods:

• Developed a computational model of mitochondrial energetics.
• Included Ca2+, proton, Na+, and phosphate dynamics.
• Accounted for distinct respiratory fluxes, pH effects, and acid-base equilibria.
• Experimentally determined NADH and membrane potential (ΔΨm) in guinea pig mitochondria.
• Compared model simulations with experimental data during various respiratory transitions.

Main Results:

• The model quantitatively reproduced experimental observations of ΔΨm, NADH levels, respiratory fluxes, and respiratory control ratio.
• Simulations mimicked the effect of phosphate addition on ΔΨm and matrix pH.
• The model qualitatively simulated respiration dependence on proton motive force and flux-force relationships.

Conclusions:

• The upgraded mitochondrial model provides a robust platform for simulating mitochondrial function.
• It offers new opportunities for studying mitochondrial dysfunction involving altered pH and ion dynamics.
• The model advances our understanding of mitochondrial bioenergetics and its regulation.