Hormone‐phase dependence of muscle sympathetic nerve activity in young healthy women using hormonal contraceptives
Bibliographic record
Abstract
The effects of hormonal contraceptives on control of muscle sympathetic nerve activity (MSNA) are unclear. We tested the hypothesis that high‐ (HH) versus low‐hormone (LH) phases of contraceptive use would not affect MSNA. Integrated MSNA recordings were obtained at rest, during −60 to−80 mmHg lower body negative pressure (LBNP) (n=4), and during combined hypercapnia‐hypoxia stress (HC‐HX) (n=7) during LH and HH. Mean arterial pressure (MAP), heart rate (HR), and cardiac output (Q) were similar between LH and HH across all conditions. Baseline MSNA burst frequency (BF; 16±8 vs 11±6 bursts/min, P =0.04) and burst incidence (BI; 23±9 vs 16±8 bursts/100hb, P =0.056) were greater during HH than LH, respectively. During LBNP, BF was greater during HH than LH (51±10 vs 43±9 at −60, P <0.001; 59±16 vs 44±11 bursts/min at −80, P =0.03), but relative increases in BF or BI were not different. The HC‐HX protocol elicited greater BI during HH than LH (29±10 vs 23±9 bursts/100hb, P =0.047), but similar BF. A subsequent HC‐HX apnea resulted in similarly high absolute BF and BI in LH and HH. Accordingly, HH tended to produce smaller relative changes in BF (+31±11 vs +39±8 bursts/min, P =0.059) and BI (+44±18 vs +54±13 bursts/100hb, P =0.053) than LH. These data indicate that hormone phase, associated with contraceptive use, influences baseline MSNA but not responses to severe reflex stimulation. 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 | 0.001 |
| 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".