The effects of cAMP on force of contraction and recovery from fatigue of fast twitch muscle is dependent on stimulation parameters
Bibliographic record
Abstract
Cyclic adenosine monophosphate (cAMP) is a potent second messenger in signal transduction and a positive inotropic regulator of cardiac muscle contractility, however effects on skeletal muscle mechanics are unclear. To determine the effect of 10 −5 M dibutyryl cAMP on post‐fatigue recovery in soleus (SOL) and extensor digitorum longus (EDL) in vitro, we stimulated SOL and EDL using varied contraction frequencies (contractions per minute; CPM) and total stimulation duration to elicit diverse fatigue profiles. SOL fatigued for 7 and 9min at 30 and 15CPM and recovered to 91.5±0.7% and 80.4±3.04% force. Long duration stimulation for 90min at 30 and 15CPM elicited 8.5±4.2% and 7.3±3.5% force restitution. SOL exposed to cAMP did not differ significantly from controls. EDL fatigued for 5 and 14 min at 10 and 2 CPM and recovered 84.1±4.1% and 81.2±1.20% force. Stimulation for 90min at 10 and 2CPM produced 7.7±1.5% and 1.2±2.9% recovery of force production. cAMP significantly improved recovery following high‐frequency stimulation (10CPM), but inhibited recovery after low‐frequency stimulation (2CPM). These results suggest that the effects of cAMP on contractility are a) fiber‐type dependent, such that only fast‐twitch fibers (EDL) respond to cAMP as an inotropic factor and b) the observed effect is dependent on stimulation parameters, namely frequency of contraction.
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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 | 0.001 |
| 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".