Abstract 9743: Profibrillatory Atrial Autonomic and Cellular Electrophysiological Remodelling with Endurance Training
Bibliographic record
Abstract
Background: Endurance exercise (Ex) increases AF risk, but underlying mechanisms are unknown. Here, we studied Ex induced autonomic and cellular electrophysiological changes controlling AF risk. Methods: Ex rats (daily treadmill training X 16 wks) were compared to matched sedentary (Sed) controls. Parasympathetic and sympathetic tone were assessed from heart rate (HR) changes caused by atropine and propranolol respectively. Baroreflex sensitivity was studied by HR responses to phenylephrine-induced BP changes. Ion currents (I KACh , I to , I CaL ) were measured in atrial myocytes by patch clamp. Atrial refractory period (ARP) was measured in vivo with transvenous electrode catheters. mRNA expression was quantified by qPCR. Results: Atrial myocytes were hypertrophied in Ex (129±8.7 pF vs 73±5 pF Sed, p<0.001). Parasympathetic tone was significantly enhanced in Ex rats by 83%, with no changes in sympathetic tone. Reflex vagal sensitivity was enhanced (60% increase in HR-reduction vs BP-increase slope with phenylephrine boluses). Post-synaptic responses were also increased, as shown by significant increases in I KACh induced by 100 μ M acetylcholine, ACh (Fig. A). mRNA expression of beta-adrenergic (β1, β2) and muscarinic (M2, M3) receptors and associated G proteins did not differ between groups. Regulatory G signaling proteins (RGS, Fig. B), which decrease ACh responses, were downregulated in Ex. Balanced downregulation of voltage gated K + and Ca 2+ current subunits (Fig. C) and currents (Fig. D) left ARP unchanged in the absence of ACh. AF inducibility was enhanced in Ex rats, an effect that was abolished by atropine. Conclusions: Ex promotes AF by enhancing vagal tone through pre (baroreflex) and post (RGS, I KACh ) synaptic mechanisms. Ion channel expression changes in a balanced way, leaving repolarization unaffected in the absence of ACh.
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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) | 0.007 | 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".