Physical and functional association of lactate dehydrogenase with mitochondria in intact and permeabilized skeletal muscle fibers
Bibliographic record
Abstract
To clarify whether mitochondria oxidize lactate, mitochondrial respiratory oxygen flux ( J O 2 ) was measured during the sequential addition of various substrates and cofactors onto permeabilized rat red (RG) and white (WG) gastrocnemius muscle fibers, as well as isolated mitochondrial subpopulations. Addition of lactate did not alter J O 2 in either RG or WG. However, subsequent addition of NAD + significantly increased J O 2 , and was abolished by the inhibitor of mitochondrial pyruvate transport, α‐hydroxycinnamate. In parallel experiments with subsarcolemmal (SS) and intramyofibrillar (IMF) mitochondria isolated from RG, only SS exhibited significant NAD + ‐ dependent lactate oxidation. To determine whether lactate dehydrogenase (LDH) is physically associated with mitochondria in RG, confocal microscopy was used to detect immunohistochemically stained LDH and mitochondrial proteins. LDH clearly colocalized with mitochondria in intact fibers. In permeabilized fibers, most of the LDH signal was lost in IMF but not SS regions. The LDH signal was absent in SS regions following trypsin treatment; however, colocalization was augmented in both SS and IMF regions with exogenous LDH + washing, suggesting LDH preferentially associates with muscle mitochondria. Collectively, these results suggest that LDH is strategically positioned within skeletal muscle fibers to functionally interact with mitochondria.
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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 | 0.001 |
| 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".