Cookies help us deliver our services. By using our services, you agree to our use of cookies. More information

Difference between revisions of "Residual oxygen consumption"

From Bioblast
Line 10: Line 10:
{{MitoPedia topics
{{MitoPedia topics
|mitopedia topic=Respiratory state
|mitopedia topic=Respiratory state
|substratestates=ROX
}}
}}
__TOC__
__TOC__
Line 35: Line 36:


=== Is the preparation fully permeabilized? ===
=== Is the preparation fully permeabilized? ===
* Non-permeabilized cells have [[ROUTINE respiration]] that
ROX may be estimated in [[mitochondrial preparations]] in [[SUIT protocol]]s which start at a respiratory state without added CHO substrates and without inhibitors, such that continuation of the SUIT protocol is possible for OXPHOS analysis. Some critical questions arise for evaluation, if this respiratory 'ROX state' represents a valid condition for estimation of ROX, and for comparison with ROX measured at the end of a SUIT protocol after titration of substrates and inhibitors of key elements of the electron transfer system (e.g. [[Rot]], [[Mna]] and [[Ama]] as inhibitors of [[CI]], [[CII]] and [[CIII]]). For evaluation of such an initial estimate of ROX, the following considerations are suggested.


# is not affected by addition of ADP,
# A preparation of [[permeabilized tissue or cells]], P<sub>tic</sub>, may contain a fraction of intact, non-permeabilized cells. Non-permeabilized cells have [[ROUTINE respiration]] that
# is higher than ROX,
## is higher than ROX;
# is not diminished over prolonged periods of time due to the presence of cellular endogenous substrates,
## is not stimulated by addition of ADP;
# can be stimulated by uncoupler titration,
## is not diminished over prolonged periods of time due to the presence of cellular endogenous substrates;
# can be inhibited by rotenone (and Ama etc.).
## can be stimulated by uncoupler titration;
Β 
## can be inhibited by Rot (CI) and Ama (CII), etc.
* Respiration of permeabilized cells incubated in a medium with significant concentrations of mitochondrial substrates
# Respiration of permeabilized tissue or cells incubated in a medium with significant concentrations of mitochondrial substrates
# is stimulated by addition of ADP,
## is higher than ROX;
# is higher than ROX,
## is stimulated by addition of ADP (compare 1.2);
# is not diminished over prolonged periods of time due to the presence of exogenous substrates in the medium,
## is not diminished over prolonged periods of time due to the presence of exogenous substrates in the medium;
# can be stimulated by uncoupler titration,
## can be stimulated by uncoupler titration,
# can be inhibited by rotenone (and Ama etc.).
## can be inhibited by Rot (CI) and Ama (CII), etc.
Β 
# In contrast, the acutal level of ROX of fully permeabilized cells responds to such tests as
* In contrast, the acutal level of ROX of fully permeabilized cells responds to such tests as
## ROX is obtained after gradual depletion of mitochondrial internal substrates (gradual decline of oxygen consumption);
# ROX is obtained after gradual depletion of mitochondrial internal substrates (gradual decline of oxygen consumption),
## ADP or uncoupler titrations accelerate this decline;
# ADP or uncoupler titrations accelerate this decline,
## Rot and Ama do not inhibit ROX;
# Rot and Ama do not inhibit ROX,
## uncoupler titration does not stimulate ROX.
# uncoupler titration does not stimulate ROX.





Revision as of 22:58, 28 January 2016


high-resolution terminology - matching measurements at high-resolution


Residual oxygen consumption

Description

ROX.jpg Residual oxygen consumption, ROX, is the respiration due to oxidative side reactions remaining after application of ETS inhibitors to mitochondrial preparations or cells, or in mt-preparations incubated without substrates (in the presence of ADP: State 2). Mitochondrial respiration is frequently corrected for ROX, then distinguishing ROX-corrected ROUTINE, LEAK, OXPHOS or ETS (R, L, P and E) from the corresponding apparent fluxes that have not been corrected for ROX (RΒ΄, LΒ΄, PΒ΄ and EΒ΄). When expressing ROX as a fraction of total respiration (flux control ratio), apparent flux not corrected for ROX should be taken as the reference. ROX may be related to, but is of course different from ROS production. Β» MiPNet article

Abbreviation: ROX

Reference: Gnaiger 2014 MitoPathways, Gnaiger 2009 Int J Biochem Cell Biol


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. 

ROX or non-mitochondrial respiration and potential artefacts

Publications in the MiPMap
Gnaiger E (2016) ROX or non-mitochondrial respiration and potential artefacts. Mitochondr Physiol Network 2016-01-28.


OROBOROS (2016) MiPNet

Abstract: ROX.jpg Residual oxygen consumption (ROX) is sometimes referred to as 'non-mitochondrial respiration'. This may be correct to a large extent, but is not entirely accurate. In a preparation of purified isolated mitochondria, a small but significant ROX is observed, even after correction for instrumental background oxygen flux. In this case, ROX is 'mitochondrial non-ETS' rather than β€˜non-mitochondrial’ respiration. In permeabilized and intact cells, ROX may be higher than in isolated mitochondria, and this increased part then would be the best measurement of non-mitochondrial respiration. Keilin (1926) introduced and accurately defined the term residual respiration.


β€’ O2k-Network Lab: AT Innsbruck Gnaiger E


Labels:




Coupling state: ETS"ETS" is not in the list (LEAK, ROUTINE, OXPHOS, ET) of allowed values for the "Coupling states" property. 

HRR: Theory 



Keilin 1929: Residual respiration

'KCN, H2S and CO combine with some of the components of oxidase forming an inactive compound, with the result that cytochrome, or at least its components a’ and c’, as well as paraphenylenediamine added to the cells, are not oxidised. The respiratory process can be still carried out through the medium of some autoxidisable carriers such as haemochromogens, haematins, the component b’ of cytochrome, or some as yet unknown autoxidisable substances. This residual respiration, according to the nature of the cell, may represent a larger or smaller fraction of the total respiration of the cell.'

Keilin D (1929) Cytochrome and respiratory enzymes. Proc R Soc London Ser B 104:206-52.


Experimental tests on ROX

Is the preparation fully permeabilized?

ROX may be estimated in mitochondrial preparations in SUIT protocols which start at a respiratory state without added CHO substrates and without inhibitors, such that continuation of the SUIT protocol is possible for OXPHOS analysis. Some critical questions arise for evaluation, if this respiratory 'ROX state' represents a valid condition for estimation of ROX, and for comparison with ROX measured at the end of a SUIT protocol after titration of substrates and inhibitors of key elements of the electron transfer system (e.g. Rot, Mna and Ama as inhibitors of CI, CII and CIII). For evaluation of such an initial estimate of ROX, the following considerations are suggested.

  1. A preparation of permeabilized tissue or cells, Ptic, may contain a fraction of intact, non-permeabilized cells. Non-permeabilized cells have ROUTINE respiration that
    1. is higher than ROX;
    2. is not stimulated by addition of ADP;
    3. is not diminished over prolonged periods of time due to the presence of cellular endogenous substrates;
    4. can be stimulated by uncoupler titration;
    5. can be inhibited by Rot (CI) and Ama (CII), etc.
  2. Respiration of permeabilized tissue or cells incubated in a medium with significant concentrations of mitochondrial substrates
    1. is higher than ROX;
    2. is stimulated by addition of ADP (compare 1.2);
    3. is not diminished over prolonged periods of time due to the presence of exogenous substrates in the medium;
    4. can be stimulated by uncoupler titration,
    5. can be inhibited by Rot (CI) and Ama (CII), etc.
  3. In contrast, the acutal level of ROX of fully permeabilized cells responds to such tests as
    1. ROX is obtained after gradual depletion of mitochondrial internal substrates (gradual decline of oxygen consumption);
    2. ADP or uncoupler titrations accelerate this decline;
    3. Rot and Ama do not inhibit ROX;
    4. uncoupler titration does not stimulate ROX.


Related terms in Bioblast

OXPHOS-coupled energy cycles. Source: The blue book

P.jpg OXPHOS, P

R.jpg ROUTINE, R

E.jpg ETS, E

L.jpg LEAK, L

ROX.jpg ROX, R


List of publications: ROX