CARNITINE PALMITOYLTRANSFERASE I ACTIVITY IS UNAFFECTED BY CALCIUM AND ENERGY CHARGE METABOLITES IN HUMAN SKELETAL MUSCLE MITOCHONDRIA
Bibliographic record
Abstract
Carnitine palmitoyltransferase I (CPTI) activity regulates the transport of long chain fatty acids into the mitochondria and is inhibited by malonyl-CoA (M-CoA) in vivo. Little is known regarding CPTI regulation in human skeletal muscle during exercise. PURPOSE To investigate the effects of physiological concentrations of calcium and energy charge metabolites on CPTI activity in intermyofibrillar (IMF) and subsarcolemmal (SS) populations of mitochondria. METHODS Nine recreationally active males volunteered for this study. IMF and SS mitochondria were extracted from the vastus lateralis muscle by homogenization and differential centrifugation. Muscle concentrations of M-CoA, calcium, and free AMP, ADP and inorganic phosphate (Pi) representative of 65% VO2max were added to IMF and SS mitochondrial preparations. CPTI activity was measured. RESULTS Maximal CPTI activity was significantly higher in IMF vs. SS mitochondria (325 ± vs. 233 ± 25, P = 0.018 nmol/min/g wm). Citrate synthase was similar in both mitochondrial fractions (2.0 ± 0.3 vs. 2.1 ± 0.3 nmol/min/g in IMF vs. SS). Addition of a physiological concentration of M-CoA (0.7 μ M) resulted in a similar inhibition of CPTI activity in IMF vs. SS mitochondria (29.9 ± 5.8% vs. 34.4 ± 5.3%). The addition of calcium, and free AMP, ADP and Pi in the presence of 0.7 μ M M-CoA had no significant effect on CPTI activity when compared to 0.7 μ M M-CoA alone in both fractions. However there was a trend (P = 0.098) for ADP to release the M-CoA inhibition in the IMF fraction. CONCLUSION Maximal CPTI activity is higher in IMF than SS mitochondria, however M-CoA sensitivity between the fractions is similar. The results suggest that calcium and energy charge metabolites do not increase CPTI activity during exercise in human skeletal muscle. Supported by NSERC & CIHR, Canada.
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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) | 0.002 | 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".