Testosterone increases lactate transport, monocarboxylate transporter (MCT) 1 and MCT4 in rat skeletal muscle
Bibliographic record
Abstract
We have examined the effects of administration of testosterone for 7 days on monocarboxylate transporter (MCT) 1 and MCT4 mRNAs and proteins in seven metabolically heterogeneous rat hindlimb muscles and in the heart. In addition, we also examined the effects of testosterone treatment on plasmalemmal MCT1 and MCT4, and lactate transport into giant sarcolemmal vesicles prepared from red and white hindlimb muscles and the heart. Testosterone did not alter MCT1 or MCT4 mRNA, except in the plantaris muscle. Testosterone increased MCT1 (20%-77%, P < 0.05) and MCT4 protein (29%-110%, P< 0.05) in five out of seven muscles examined. In contrast, in the heart MCT1 protein was not increased (P> 0.05), and MCT 4 mRNA and protein were not detected. There was no correlation between the testosterone-induced increments in MCT1 and MCT4 proteins. Muscle fibre composition was not associated with testosterone-induced increments in MCT1 protein. In contrast, there was a strong positive relationship between the testosterone-induced increments in MCT4 protein and the fast-twitch fibre composition of rat muscles. Lactate transport into giant sarcolemmal vesicles was increased in red (23%, P< 0.05) and white muscles (21%, P< 0.05), and in the heart (58%, P< 0.05) of testosterone-treated animals (P< 0.05). However, plasmalemmal MCT1 protein (red, +40%, P< 0.05; white, +39%, P< 0.05) and plasmalemmal MCT4 protein (red, +25%, P< 0.05; white, +48%, P< 0.05) were increased only in skeletal muscle. In the heart, plasmalemmal MCT1 protein was reduced (-20%, P< 0.05). In conclusion, these studies have shown that testosterone induces an increase in both MCT1 and MCT4 proteins and their plasmalemmal content in skeletal muscle. However, the testosterone-induced effect was tissue-specific, as MCT1 protein expression was not altered in the heart. In the heart, the testosterone-induced increase in lactate transport cannot be explained by changes in plasmalemmal MCT1 content, but in skeletal muscle the increase in the rate of lactate transport was associated with increases in plasmalemmal MCT1 and MCT4.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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".