Cell ergometry

high-resolution terminology - matching measurements at high-resolution

Cell ergometry

Description

Biochemical cell ergometry aims at measurement of J_O2,max (compare V_O2,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 P_i 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. 

960px High-resolution pdf: »File:OROBOROS Poster HRR.pdf

-

Figure 1: Phosphorylation control protocol in the intact cell

1. ETS coupling efficiency: j_≈E = ≈E/E = (E-L)/E
2. ETS excess factor over R: Ex_R/E = (E-R)/E
3. ROUTINE phosphorylation control factor: j_≈R = ≈R/R =(R-L)/R
4. ROUTINE phosphorylation control ratio: ≈R/E = (R-L)/E

Ergometry

V_O2max or V_O2peak 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 V_O2peak to J_O2peak expressed in SI units [pmol·s^-1·mg^-1]:

1 ml O2·min-1·kg-1 = 0.744 µmol·s-1·kg-1

V_O2peak (J_O2peak) 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.