Cell ergometry

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{{MitoPedia |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 of 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 ([[E-P control efficiency |E-P control efficiency) and to calculate the P-L control efficiency jP-L and E-L coupling efficiency jE-L. These normalized flux ratios are the basis to calculate the ergometric or ergodynamic efficiency, ε = j · f, where f is the normalized force ratio.

» MiPNet article |info=Gnaiger 2020 MitoPathways, Oxygen flux }}

Cell ergometry and OXPHOS

Publications in the MiPMap
Gnaiger E (2015) Cell ergometry and OXPHOS. Mitochondr Physiol Network 2015-01-18.

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Oroboros (2015) MiPNet

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


Cell ergometry.pdf

Spiroergometry

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.

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Mitochondrial and cellular respiratory rates in coupling-control states

OXPHOS-coupled energy cycles. Source: The Blue book
» Baseline state
Respiratory rate Definition Icon
OXPHOS capacity P = -Rox P.jpg mt-preparations
ROUTINE respiration R = -Rox R.jpg living cells
ET capacity E = -Rox E.jpg » Level flow
» Noncoupled respiration - Uncoupler
LEAK respiration L = -Rox L.jpg » Static head
» LEAK state with ATP
» LEAK state with oligomycin
» LEAK state without adenylates
Residual oxygen consumption Rox L = -Rox ROX.jpg
  • Chance and Williams nomenclature: respiratory states
» State 1 —» State 2 —» State 3 —» State 4 —» State 5

Flux control ratios related to coupling in mt-preparations and living cells

» Flux control ratio
» Coupling-control ratio
» Coupling-control protocol
FCR Definition Icon
L/P coupling-control ratio L/P L/P coupling-control ratio » Respiratory acceptor control ratio, RCR = P/L
L/R coupling-control ratio L/R L/R coupling-control ratio
L/E coupling-control ratio L/E L/E coupling-control ratio » Uncoupling-control ratio, UCR = E/L
P/E control ratio P/E P/E control ratio
R/E control ratio R/E R/E control ratio
net P/E control ratio (P-L)/E net P/E control ratio
net R/E control ratio (R-L)/E net R/E control ratio

Net, excess, and reserve capacities of respiration

Respiratory net rate Definition Icon
P-L net OXPHOS capacity P-L P-L net OXPHOS  capacity
R-L net ROUTINE capacity R-L R-L net ROUTINE capacity
E-L net ET capacity E-L E-L net ET capacity
E-P excess capacity E-P E-P excess capacity
E-R reserve capacity E-R E-R reserve capacity

Flux control efficiencies related to coupling-control ratios

» Flux control efficiency jZ-Y
» Background state
» Reference state
» Metabolic control variable
Coupling-control efficiency Definition Icon Canonical term
P-L control efficiency jP-L = (P-L)/P = 1-L/P P-L control efficiency P-L OXPHOS-flux control efficiency
R-L control efficiency jR-L = (R-L)/R = 1-L/R R-L control efficiency R-L ROUTINE-flux control efficiency
E-L coupling efficiency jE-L = (E-L)/E = 1-L/E E-L coupling efficiency E-L ET-coupling efficiency » Biochemical coupling efficiency
E-P control efficiency jE-P = (E-P)/E = 1-P/E E-P control efficiency E-P ET-excess flux control efficiency
E-R control efficiency jE-R = (E-R)/E = 1-R/E E-R control efficiency E-R ET-reserve flux control efficiency

General

» Basal respiration
» Cell ergometry
» Dyscoupled respiration
» Dyscoupling
» Electron leak
» Electron-transfer-pathway state
» Hyphenation
» Oxidative phosphorylation
» Oxygen flow
» Oxygen flux
» Permeabilized cells
» Phosphorylation system
» Proton leak
» Proton slip
» Respiratory state
» Uncoupling



MitoPedia concepts: MiP concept, Ergodynamics 


MitoPedia methods: Respirometry 


Labels:




Regulation: Coupling efficiency;uncoupling  Coupling state: LEAK, OXPHOS, ET  Pathway: N, S, NS, ROX  HRR: Theory