Sympathetic neural recruitment during severe chemoreflex stimulation (LB732)
Bibliographic record
Abstract
Sympathetic neural recruitment during severe chemoreflex stimulation Mark B. Badrov 1 , Charlotte W. Usselman 1 , J. Kevin Shoemaker 1,2 : 1 School of Kinesiology, 2 Department of Physiology and Pharmacology, Western University, London, Ontario, Canada This study tested the hypothesis that severe chemoreflex stress stimulates the recruitment of sub‐populations of previously silent, larger amplitude sympathetic action potentials. Muscle sympathetic nerve activity was measured via microneurography in 7 healthy males (27 ± 2 yrs, 180 ± 4 cm, 82 ± 13 kg; mean ± SD) at baseline and during a maximal end‐inspiratory apnea, which was preceded by a rebreathing protocol designed to elicit progressive hypoxia and hypercapnia, thereby maximizing the severity of sympathoexcitation evoked during the subsequent apnea (End‐apnea: PO 2 = 58 ± 4 Torr; PCO 2 = 55 ± 5 Torr). Compared to baseline, burst frequency (19 ± 6 to 43 ± 10 bursts/min; P < 0.01), burst incidence (37 ± 12 to 73 ± 11 bursts/100 heartbeats; P < 0.01), and mean normalized burst amplitude (30 ± 6 to 56 ± 6 AU; P < 0.001) were increased during apnea. For sympathetic action potential analyses, action potential frequency (211 ± 205 to 617 ± 354 spikes/min; P < 0.01), action potential incidence (408 ± 400 to 1068 ± 598 spikes/100 heartbeats; P < 0.001), and mean action potential content per burst (10 ± 6 to 15 ± 9 spikes/burst; P < 0.05) were increased during apnea compared to baseline. Furthermore, the total number of distinct amplitude‐based ‘clusters’ of action potentials increased from 15 ± 5 at baseline to 19 ± 8 during apnea ( P < 0.05). This was concomitant with an increase in the number of distinct ‘clusters’ per sympathetic burst (5 ± 2 to 6 ± 3 clusters/burst; P < 0.01) during apnea. In conclusion, a neural recruitment strategy exists whereby previously silent sub‐populations of larger amplitude action potentials are recruited as sympathetic activity is elevated during periods of severe chemoreflex stress. Grant Funding Source : Supported by NSERC and CIHR
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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) | 0.001 | 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".