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Abbreviation: NS(PGM)

Reference: C MiPNet18.13 IOC84 Alaska

SUIT protocol pattern: 1PGM;2D;3S;4U;5Rot-


1PGM;2D;2c;3S;4U;5Rot;6Ama.png 1PGM;2D;2c;3S;4U;5Rot;6Ama

SUIT states: 1-2PGM(LPc);3-4PGMS(PE);5S;6ROX
Step Respiratory state Pathway control Pathway to Q Comment
1PGM PGM(L) N CI LEAK state with type N substrates, NL: Non-phosphorylating resting state with NADH-linked (type N) substrates pyruvate&glutamate&malate (PGM; without adenalytes; CI-linked pathway to Q). See 2D.

2D PGM(P) N CI OXPHOS capacity with type N substrates, NP: Respiratory capacity in the active coupled state (PGM with ADP). PGM ensures a higher N-pathway flux, if PM- or GM-pathway capacity is lower than PGM. Compared to PM, the contribution of the S-pathway may be higher with PGM. Compare 1PM;2D;3U;4S;5Rot- and 1PM;2D;3U;4G;5S;6Oct;7Rot;8Gp- .
D(c) PGM(c) N CI Cytochrome c test for quality control of the integrity of the outer mitochondrial membrane (loss of cytochrome c is indicated by a stimulation of respiration). Cytochrome c added immediately after the earliest ADP-activation step. Application of the cytochrome c test early in the protocol ensures comparability of all states in case of any effect of c (Gnaiger 2007 MitoPathways).
3S PGMS(P) NS CI&II OXPHOS capacity with type NS substrates (CI&II-linked pathway to Q), NSP: Respiratory stimulation by convergent electron flow through Complexes I&II at the Q-junction, in the coupled state after further addition of succinate (S), as an estimate of OXPHOS capacity with reconstitution of the TCA cycle (Gnaiger 2009 Int J Biochem Cell Biol).
4U PGMS(E) NS CI&II electron transfer-pathway (ET-pathway) capacity with type NS substrates, NSE: Uncoupling by CCP or FCCP titration (avoiding inhibition by high uncoupler concentrations), as a test for limitation of OXPHOS relative to ET capacity by the phosphorylation system. Limitation: The additive effect of N+S measured separately compared to the combined NS pathway cannot be evaluated in the same coupling state. With NP, NSP, NSE, and SE. If independent information is available on SP = SE, the additivity can be calculated for the OXPHOS state.
5Rot S(E) S CII ET capacity with type S (CII) substrate, SE: ET capacity with succinate, after blocking Complex I with rotenone. Limitation: A succinate concentration of >10 mM may be required for saturating SE capacity.
6Ama ROX Residual oxygen consumption (ROX) due to oxidative side reactions, estimated after addition of antimycin A (inhibitor of Complex III). ROX may be lower in substrate states earlier in the SUIT protocol. Therefore, this ROX measurement is frequently taken as a methodological control rather than as the final basis of ROX correction of mitochondrial respiration (mt).


MitoPedia concepts: SUIT protocol, SUIT B