AICAR-STIMULATED AMP-KINASE ACTIVATION INCREASES FATTY ACID OXIDATION AT REST, BUT IS NOT ADDITIVE TO CONTRACTION.
Bibliographic record
Abstract
BACKGROUND AMP-activated protein kinase (AMPK) is an important metabolic enzyme in energy sensing and ATP provision in skeletal muscle. AMPK is activated allosterically at rest with 5- aminoimidazole-4-carboxamide-riboside (AICAR) and both covalently (AMPKK) and allosterically (increased AMP, creatine) during contraction. Once activated, AMPK phosphorylates downstream targets, acutely increasing glucose uptake and free fatty acid (FFA) oxidation (OX), while decreasing its esterification (EST). However, there are relatively few studies characterizing AMPK's role in lipid metabolism, and the effects of acute AMPK stimulation by AICAR have not been examined during contraction. PURPOSE To examine FFA OX and EST (diacylgylcerol (DG) + triacylglycerol (TG)) in isolated soleus muscle both at rest and during contraction (20 tetani/min), in the presence or absence of AICAR. It was hypothesized that AICAR would have no additional effect on contraction-induced changes in FFA metabolism. METHODS Pulse-chase procedures were used in incubated resting or contracting (20 tetani/min) rat soleus muscle in the presence and absence of 2 mM AICAR. RESULTS AICAR increased OX at rest (+17.76 nmol/g; P=0.01), while having no significant effect on DG or TG EST. However, AICAR treatment caused a significant increase in the partitioning of FFA by increasing the OX: EST (DG+TG) ratio (0.45, control vs 0.66, AICAR; P=0.03). With contraction, OX increased by 58%, and DG and TG EST increased by 33% and 30%, respectively. However, AICAR had no further additive effect on the contraction-induced increase in OX, nor did it blunt the contraction-induced increase in EST. AICAR had no significant effect on total uptake (DG+TG+OX) at rest or during contraction. CONCLUSION AICAR acutely partitions FFA towards OX, but is not additive to the contraction-induced increase in OX, suggesting that AMPK is the prominent enzyme that increases FFA utilization during contraction. Future studies will characterize the role of AMPK in regulating lipolysis. 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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 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 | 0.001 |
| Insufficient payload (model declined to judge) | 0.004 | 0.001 |
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".