Veno-Constriction of the Basilic Vein with Systemic Sympathetic Activation in Humans
Bibliographic record
Abstract
Cardiac function is determined to a large extent by central venous volume-dependent cardiac filling pressure. Controlling the distribution of blood volume between the central and peripheral veins is therefore a key component of cardiovascular function. Reduction in peripheral venous volume via the muscle pump or vasoconstriction-induced passive venous recoil is well documented. However, in humans little is known about sympathetic venoconstriction, especially in larger conduit veins that drain the leg or arm. PURPOSE: To determine whether systemic sympathetic nervous system activation (SNA) can induce veno-constriction in human limb conduit veins. METHODS: 10 Male subjects lay supine with arms extended at heart level. Heart rate (HR) and mean arterial blood pressure (MAP) were measured using electrocardiogram (ECG) and arterial tonometry. Echo ultrasound was used to continuously measure basilic vein diameter ∼10–15 cm above the left elbow. Venous pressure was kept constant at 40 mmHg via inflation of a pressure cuff placed proximal to the site if vessel imaging. There were four experimental interventions: Physical Stress Evoked SNA (PS; maintained, vigorous lower limb isometric contraction), Mental Stress Evoked SNA (MS; STROOP word color test) Emotional Stress Evoked SNA (ES; anger interview), and a control condition (C; counting forward by one). Venous diameter was measured over 4 repeats of 2 minute baseline, 2 minute intervention, 4 minute recovery periods. The order of interventions was counter balanced. RESULTS: All data are mean VSE. All three SNA interventions resulted in significant reductions in venous diameter (mm) (baseline vs. intervention): PS – 5.91 ± 0.15 vs. 4.66 ± 0.26, P<0.05; MS – 5.85 ± 0.15 vs. 4.88 ± 0.16, P<0.05; ES – 5.90 ± 0.10 vs. 4.66 ± 0.32, P<0.05. No change was observed in the control intervention C – 5.91 ± 0.11 vs. 5.80 ± 0.12, P=NS. All three SNA interventions evoked significant increases in MAP (mmHg) (baseline vs. intervention): PS – 80.72 ± 1.81 vs. 112.50 ± 1.84, P<0.05; MS- 82.52 ± 1.86 vs. 96.12 ± 3.37, P<0.05; ES – 81.00 ± 2.49 vs. 91.71 ± 5.19, P<0.05. No change was observed in the control intervention C – 80.19 ± 2.39 vs. 83.11 ±2.90, P<0.05). CONCLUSION: Activation of systemic sympathetic nervous activity resulting in the elevation of arterial blood pressure is accompanied by constriction of the basilic conduit vein in humans. This confirms sympathetic innervation of this vein in humans and the capacity for human conduit vein volume to be regulated via sympathetic activation. Supported by: Natural Sciences and Engineering Research Council of Canada, Canada Foundation for Innovation, Ontario Innovation Trust
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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".