- high-resolution terminology - matching measurements at high-resolution
Cell ergometry
Description
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 ETS 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 ETS excess over OXPHOS capacity and to calculate OXPHOS- and ETS coupling efficiencies, 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.
Abbreviation: n.a.
Reference: Gnaiger 2014 MitoPathways
MitoPedia methods:
Respirometry
MitoPedia topics: "Respiratory state" is not in the list (Enzyme, Medium, Inhibitor, Substrate and metabolite, Uncoupler, Sample preparation, Permeabilization agent, EAGLE, MitoGlobal Organizations, MitoGlobal Centres, ...) of allowed values for the "MitoPedia topic" property.
Respiratory state"Respiratory state" is not in the list (Enzyme, Medium, Inhibitor, Substrate and metabolite, Uncoupler, Sample preparation, Permeabilization agent, EAGLE, MitoGlobal Organizations, MitoGlobal Centres, ...) of allowed values for the "MitoPedia topic" property.
- 
Figure 1: Phosphorylation control protocol in the intact cell
- ETS coupling efficiency, E-L control factor: j≈E = ≈E/E = (E-L)/E = 1-L/E
- ROUTINE coupling efficiency: j≈R = ≈R/R =(R-L)/R
- netROUTINE control ratio: ≈R/E = (R-L)/E
- Excess E-R capacity factor: jExR = (E-R)/E
Ergometry
VO2max or VO2peak in cycle or treadmill ergometry 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) to convert VO2peak to JO2peak expressed in SI units [nmol·s-1·g-1]:
1 ml O2·min-1·kg-1 = 0.744 µmol·s-1·kg-1
VO2peak (JO2peak) 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.
