MITOCHONDRIAL MEMBRANE REMODELLING AND RESPIRATION DURING CONTRACTILE ACTIVITY-INDUCED MITOCHONDRIAL BIOGENESIS
Bibliographic record
Abstract
Intermyofibrillar and subsarcolemmal mitochondria (IFM and SSM) exist in skeletal muscle, and these increase in response to chronic contractile activity (CCA). IFM and SSM contain the adenine nucleotide translocase (ANT), ATP synthase (F1ATPase), porin, and uncoupling protein-3 (UCP3) that are responsible for proton leak, resulting in state 4 respiration. PURPOSE To investigate the relationship between these proteins and state 4 respiration during CCA-induced mitochondrial biogenesis. METHODS Chronic (10-Hz) stimulation (3 h/day, 7 days) was used to induce CCA of rat muscle. Respiration was measured in SSM and IFM with the additions of glutamate (state 4), oleic acid (OA) and GDP. OA stimulates, while GDP inhibits UCP3 function. Immunoblotting was used to measure protein levels. Cytochrome c oxidase (COX) activity was used as a marker of mitochondrial biogenesis. RESULTS UCP3, F1α subunit of F1ATPase (F1α) and porin were 1.3-, 1.6- and 1.5-fold (p < .05) greater in IFM compared to SSM. CCA increased COX activity by 1.4-fold (p < .05). UCP3 content was increased by 1.9- and 2.3-fold in IFM and SSM, respectively. CCA increased F1α in SSM by 1.3-fold, but had no effect in IFM. ANT and porin were not changed by CCA. CCA increased state 4 respiration by 1.4-fold (p < .05) in IFM, but no effect was seen in the SSM. OA stimulated state 4 respiration by 2-fold in IFM, but there was no effect in SSM despite only modestly lower UCP3 levels in SSM. Inhibition of UCP3 function by GDP led to 55–70% reductions in state 4 respiration, independent of the 2-fold difference in UCP3 content due to CCA. CONCLUSIONS CCA induced changes in protein composition within IFM and SSM membranes, including an increase in UCP3 expression which exceeded the extent of mitochondrial biogenesis. Modifications in UCP3 function affect state 4 respiration, but a dissociation of UCP3 content from state 4 respiration suggests that respiration is differentially regulated in SSM and IFM, by multiple membrane components. Supported by NSERC.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".