Influence of spontaneous bursts of muscle sympathetic nerve activity on the femoral artery and vein flow in young healthy adults
Bibliographic record
Abstract
Spontaneously occurring bursts of sympathetic nerve activity contribute to the moment-to-moment control of blood pressure by evoking an alpha-adrenergic mediated arterial vasoconstriction. However, the venous system also receives a rich sympathetic innervation, contains alpha-adrenergic receptors, and venoconstriction has been elicited by sympatho-excitatory stimuli (e.g., hypoxia, exercise) in some studies. Herein we tested the hypothesis that spontaneously occurring bursts of sympathetic activity evoke dynamic changes in venous tone and consequently, flow. In nine healthy volunteers (4 women, 26±7 years, 24±4 kg·m 2 ; mean±SD) simultaneous 10-minute recordings of femoral artery and vein blood flow (duplex ultrasound), muscle sympathetic nerve activity (MSNA, microneurography), and blood pressure (finger photoplethysmography) were made. Sympathetic transduction was quantified as the change in mean arterial pressure (MAP), femoral artery flow, and femoral vein flow, following spontaneous bursts of MSNA using signal-averaging techniques. As expected, sympathetic bursts were accompanied by a transient increase in MAP (peak +3.2±1.2 mmHg), while MAP fell following cardiac cycles not associated with a sympathetic burst (nadir -1.1±0.6 mmHg). Similarly, sympathetic bursts were followed by a transient decrease in femoral artery blood flow (nadir -9.2±4.6 ml/min), whereas increases were exhibited following cardiac cycles not associated with a sympathetic burst (peak +2.5±2.6 ml/min). In contrast, sympathetic bursts evoked comparatively smaller, less consistent and directionally opposite changes in femoral vein flow (average over 15 cardiac cycles +2.1±6.0 ml/min), while small decreases were observed following cardiac cycles not associated with a sympathetic burst (-0.8±1.7 ml/min). Collectively, these findings indicate that spontaneously occurring bursts of sympathetic nerve activity exert a minimal contribution to the moment-to-moment control of femoral venous flow in young healthy humans. Further studies examining sympathetic venous transduction during physiological stressors (e.g., exercise), and in other venous beds (e.g., mesenteric) and populations (e.g., hypertension) are warranted. JPF is supported by a Health Research Council Programme grant (19/687). This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.
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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) | 0.000 | 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) | 0.000 | 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".