Biochemical cell ergometry aims at measurement of JO2max (compare VO2max or VO2peak in exercise ergometry of humans and animals) of cell respiration linked to phosphorylation of ADP to ATP. The corresponding OXPHOS capacity is based on saturating concentrations of ADP, [ADP]*, and inorganic phosphate, [Pi]*, available to the mitochondria. This is metabolically opposite to uncoupling respiration, which yields ET capacity. The OXPHOS state can be established experimentally by selective permeabilization of cell membranes with maintenance of intact mitochondria, titrations of ADP and Pi to evaluate kinetically saturating conditions, and establishing fuel substrate combinations which reconstitute physiological TCA cycle function. Uncoupler titrations are applied to determine the apparent ET-pathway excess over OXPHOS capacity and to calculate OXPHOS- and ET-coupling efficiency , j≈P and j≈E. These normalized flux ratios are the basis to calculate the ergometric or ergodynamic efficiency, ε = j · f, where f is the normalized force ratio.
- 1 Description
- 2 Cell ergometry and OXPHOS
- 2.1 Spiroergometry
- 2.2 Cell ergometry: intact cells
- 2.3 Cell ergometry: permeabilized cells
Cell ergometry and OXPHOS
|Gnaiger E (2015) Cell ergometry and OXPHOS. Mitochondr Physiol Network 2015-01-18.|
Abstract: Spiroergometry on the organismic level is compared to cell ergometry as OXPHOS analysis on the cellular level.
• O2k-Network Lab: AT Innsbruck Gnaiger E
Figure 1: Coupling-control protocol in the intact cell
- VO2max or VO2peak in cycle or treadmill spiroergometry is expressed in units of [mL O2·min-1·kg-1] body mass. 1 mL oxygen at STPD is equivalent to 22.392 mmol O2. Therefore, multiply by 1000/(22.392·60)=0.744 to convert VO2max to JO2max expressed in SI units [nmol·s-1·g-1]:
1 mL O2·min-1·kg-1 = 0.744 µmol·s-1·kg-1
- VO2max (JO2max) typically declines from 70 to 25 mL O2·min-1·kg-1 (50 to 20 µmol·s-1·kg-1) in the range of healthy trained to obese untrained humans.
Cell ergometry: intact cells
Respiratory coupling states in intact cells
Respiratory coupling control ratios in intact cells
Respiratory coupling control factors in intact cells
Cell ergometry: permeabilized cells
Respiratory coupling states in mt-preparations
Respiratory coupling control ratios in mt-preparations
Respiratory coupling control factors in mt-preparations
MitoPedia methods: Respirometry
Regulation: Coupling efficiency;uncoupling Coupling state: LEAK, OXPHOS, ET Pathway: N, S, NS, ROX HRR: Theory