Sympathetic transduction of blood pressure during graded lower body negative pressure in young healthy adults
Bibliographic record
Abstract
Sympathetic transduction of blood pressure (BP) is correlated negatively with resting muscle sympathetic nerve activity (MSNA) in cross-sectional data, but the acute effects of increasing MSNA are unclear. Sixteen (4 female) healthy adults (26 ± 3 years) underwent continuous measurement of heart rate, BP, and MSNA at rest and during graded lower body negative pressure (LBNP) at −10, −20, and −30 mmHg. Sympathetic transduction of BP was quantified in the time (signal averaging) and frequency (MSNA-BP gain) domains. The proportions of MSNA bursts firing within each tertile of BP were calculated. As expected, LBNP increased MSNA burst frequency ( P < 0.01) and burst amplitude ( P < 0.02), although the proportions of MSNA bursts firing across each BP tertile remained stable (all P > 0.44). The MSNA-diastolic BP low-frequency transfer function gain ( P = 0.25) was unchanged during LBNP; the spectral coherence was increased ( P = 0.03). Signal-averaged sympathetic transduction of diastolic BP was unchanged (from 2.1 ± 1.0 at rest to 2.4 ± 1.5, 2.2 ± 1.3, and 2.3 ± 1.4 mmHg; P = 0.43) during LBNP, but diastolic BP responses following nonburst cardiac cycles progressively decreased (from −0.8 ± 0.4 at rest to −1.0 ± 0.6, −1.2 ± 0.6, and −1.6 ± 0.9 mmHg; P < 0.01). As a result, the difference between MSNA burst and nonburst diastolic BP responses was increased (from 2.9 ± 1.4 at rest to 3.4 ± 1.9, 3.4 ± 1.9, and 3.9 ± 2.1 mmHg; P < 0.01). In conclusion, acute increases in MSNA using LBNP did not alter traditional signal-averaged or frequency-domain measures of sympathetic transduction of BP or the proportion of MSNA bursts firing at different BP levels. The factors that determine changes in the firing of MSNA bursts relative to oscillations in BP require further investigation.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.002 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".