Reference: A: simultaneous determination of O2 flux and mt-membrane potential
This is a protocol to investigate the N- and NS-pathway control state on isolated mitochondria and tissue homogenate. The protocol can be applied to cells or tissue types that display a preference for either GM over PM to support NADH-linked respiration or vice versa. Oligomycin (Omy) is used to induce a LEAK state of respiration via the inhibition of the ATP synthase. Since higher concentrations of Omy can decrease the ET state induced upon addition of uncoupler, the required concentration of Omy has to be assessed by the Omy titration test. This is an ideal protocol for simultaneous determination of O2 flux and mitochondrial membrane potential on isolated mitochondria and tissue homogenate. SUIT-020 O2 mt D032 is a protocol which can be performed without the fluorescence dye as well.
Communicated by Huete-Ortega M, Komlodi T, Gnaiger E (last update 2019-07-05)
Specific SUIT protocols
SUIT-020 Fluo mt D033
SUIT-020 O2 mt D032
- SUIT-020 O2 mt D032 determination of O2 flux on isolated mitochondria and tissue homogenate as a control for SUIT-020 Fluo mt D033.
Steps and respiratory states
|Step||State||Pathway||Q-junction||Comment - Events (E) and Marks (M)|
|Step||Respiratory state||Pathway control||ET-Complex entry into Q-junction||Comment|
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- Pathway control
Strengths and limitations
- NS-OXPHOS capacity provides a physiologically relevant estimate of maximum mitochondrial respiratory capacity.
- Comparison of GM- with PM-capacity yields important information on N-pathway respiratory control upstream of CI.
- A succinate concentration of >10 mM may be required for saturating SE capacity.
- Nigericin as a H+/K+ antiporter can be used to dissipate transmembrane pH gradient, which results in increased mt-membrane potential in the LEAK state.
- + You obtain information in a single protocol about the NS-, S and N- pathway control state.
- + The protocol can be combined with fluorescence dyes to evaluate mitochondrial membrane potential.
- - Many fluorescence dyes (such as Safranin, TMRM etc) can inhibit components of the ET system, most commonly affecting NADH-linked respiration. Therefore, a control run of the protocol should be done in the absence of the fluorescence dye. The following protocols can be used: SUIT-020 O2 mt D032, SUIT-021 O2 mt D035.
- - CIV activity cannot be determined and Cytochrome c test cannot be performed together with the fluorescence dyes.
- - Oligomycin concentration has to be determined. Higher concentrations of Oligomycin may inhibit the ET state.
- - Careful washing is required after the experiment to avoid carry-over of the inhibitors and uncoupler.
Compare SUIT protocols
- SUIT-001;SUIT-001 O2 mt D001for isolated mitochondria and tissue homogenate: a complex protocol to get information not only about the NS(PGM) in the OXPHOS state, but also in ET state and about the FGp-pathways additionally.
- SUIT-004;SUIT-004 O2 pfi D010: it provides an information about the NS(PM) pathway in the ET state without the contribution of G.
- SUIT-008;SUIT-008 O2 pfi D014 and SUIT-008 O2 ce-pce D025: it provides information about the NS(PGM) pathway in the OXPHOS and ET-states, but without the addtion of Omy.
- SUIT-012:it provides information about the N(PGM) pathway in the OXPHOS and ET-states without the contribution of S-pathway and without the addition of Omy.
|MiPNet20.13 Safranin mt-membranepotential||2019-06-24||Mouse||Nervous system|
|Krumschnabel 2014 Methods Enzymol||2014||Krumschnabel G, Eigentler A, Fasching M, Gnaiger E (2014) Use of safranin for the assessment of mitochondrial membrane potential by high-resolution respirometry and fluorometry. Methods Enzymol 542:163-81.||Mouse||Nervous system|