Description
Biochemical cell ergometry aims at measurement of JO2,max (compare VO2,max 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.
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.
File:Cell ergometry.jpg High-resolution pdf: Β»
Figure 1: Phosphorylation control protocol in the intact cell
- ETS coupling efficiency: jβE = βE/E = (E-L)/E
- ROUTINE phosphorylation control factor: jβR = βR/R =(R-L)/R
- ROUTINE phosphorylation control ratio: βR/E = (R-L)/E
- ETS excess factor over R: jExR = (E-R)/E
Ergometry
VO2max or VO2peak in cycle or treadmill ergometry is expressed in units of [ml O2Β·min-1Β·kg-1] body mass. 1 ml oxygen at STPD is equivalent to 22.392 mmol O2. Therefore, multiply by 1000/(22.392Β·60) to convert VO2peak to JO2peak expressed in SI units [pmolΒ·s-1Β·mg-1]:
1 ml O2Β·min-1Β·kg-1 = 0.744 Β΅molΒ·s-1Β·kg-1
VO2peak (JO2peak) typically declines from 70 to 25 ml O2Β·min-1Β·kg-1 (50 to 20 Β΅molΒ·s-1Β·kg-1) in the range of healthy trained to obese untrained humans.