MiPNet12.01 Suppl T-issue: Difference between revisions

Revision as of 12:30, 4 December 2019

MiPNet12.01 Suppl T-issue

MitoPathways at the Q-junction: mouse skeletal muscle fibers.

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Oroboros (2018-11-18) Mitochondr Physiol Network

Abstract: Oroboros (2018) MitoPathways at the Q-junction: mouse skeletal muscle fibers. Mitochondr Physiol Network 12.01(03): Suppl T-issue. » Versions

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• O2k-Network Lab: AT_Innsbruck_Oroboros

Labels: MiParea: Respiration

Organism: Mouse Tissue;cell: Skeletal muscle Preparation: Permeabilized tissue

Coupling state: LEAK, ROUTINE, ET Pathway: N, S, NS, ROX HRR: Oxygraph-2k, O2k-Protocol

MitoPathways, O2k-Demo, O2k-Core

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-== Limitations of the SUIT protocol ==
-=== Maximum OXPHOS and ET-capacity ===
-:::: Evaluation of maximum respiratory capacities requires titration of further substrates activating additional [[respiratory complexes]] at the Q-junction ([[Electron-transferring flavoprotein complex |CETF]] and [[glycerophosphate dehydrogenase complex |CGpDH<]]).
-=== Malate concentration ===
-:::: The [[malate]] concentration was 2 mM, to saturate N-linked respiration. However, at 2 mM malate, the fumarate concentration is increased to a level which inhibits succinate dehydrogenase. Then NS- and S-linked respiratory capacities are underestimated. A malate concentration of 0.5 mM, which saturates N-linked respiration and inhibits S-linked respiration to a lesser extent, represents and improved standard.
-::::» [[Talk:Malate |Optimum malate concentration in SUIT protocols]]
-=== ROX correction ===
-:::: The fact that ROX was higher in the NS-substrate state compared to N-linked LEAK respiration indicates that ROX is partially controlled by the substrate state. Therefore, a single measurement of ROX cannot be applied for correction of total oxygen consumption in the different substrate states. Total respiration, therefore, represents apparent coupling states ''L''´, ''P''´ and ''E''´ (Fig. 1). ROX correction is possible in the present experiment only for NS- and S-linked respiration. [[Azide]] inhibits not only CIV but other heme-based oxidases and peroxidases, and therefore may interfere with ROX beyond blocking respiratory electron transfer. Based on this argument, a combination of CII- and CIII-inhibitors (malonic acid, antimycin A, myxothiazol) may yield more consistent results, although any ROS scavenged by cytochrome ''c'' may in the absence of a CIV-inhibitor result in respiratory oxygen consumption through CIV.