Parallel activation of mitochondrial oxidative metabolism with increased cardiac energy expenditure is not dependent on fatty acid oxidation in pigs
Bibliographic record
Abstract
Steady state concentrations of ATP and ADP in vivo are similar at low and high cardiac workloads; however, the mechanisms that regulate the activation of substrate metabolism and oxidative phosphorylation that supports this stability are poorly understood. We tested the hypotheses that (1) there is parallel activation of mitochondrial and cytosolic dehydrogenases in the transition from low to high workload, which increases NADH/NAD+ ratio in both compartments, and (2) this response does not require an increase in fatty acid oxidation (FAO). Anaesthetized pigs were subjected to either sham treatment, or an abrupt increase in cardiac workload for 5 min with dobutamine infusion and aortic constriction. Myocardial oxygen consumption and FAO were increased 3- and 2-fold, respectively, but ATP and ADP concentrations did not change. NADH-generating pathways were rapidly activated in both the cytosol and mitochondria, as seen in a 40% depletion in glycogen stores, a 3.6-fold activation of pyruvate dehydrogenase, and a 50% increase in tissue NADH/NAD+. Simulations from a multicompartmental computational model of cardiac energy metabolism predicted that parallel activation of glycolysis and mitochondrial metabolism results in an increase in the NADH/NAD+ ratio in both cytosol and mitochondria. FAO was blocked by 75% in a third group of pigs, and a similar increase in and the NAHD/NAD+ ratio was observed. In conclusion, in the transition to a high cardiac workload there is rapid parallel activation of substrate oxidation that results in an increase in the NADH/NAD+ ratio.
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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 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| 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".