Dissociation between reflex sympathetic and forearm vascular responses to lower body negative pressure in heart failure patients with coronary artery disease
Bibliographic record
Abstract
Many heart failure (HF) patients exhibit paradoxical forearm vasodilation when central blood volume is reduced by lower body negative pressure (LBNP). We tested the hypothesis that this response results from reflex sympathetic withdrawal. We recorded simultaneously forearm blood flow, muscle sympathetic nerve activity (MSNA), and plasma norepinephrine (PNE) during four random applications of LBNP, -5, -10, -20, and -40 mmHg, in 12 men with HF (mean left ventricular ejection fraction = 24 + or - 2%) and 10 healthy, normal, age-matched men (N). Compared with N, MSNA burst frequency (P = 0.001) and PNE (P = 0.005) were significantly higher in the HF group, both at rest and during LBNP. As anticipated in N, LBNP -40 mmHg significantly increased MSNA (+14.2 + or - 2.5 bursts/min; P < 0.05) and PNE (+0.83 + or - 0.22 nmol/l; P < 0.05) and decreased forearm vascular conductance (FVC) (-11.7 + or - 3.2 ml.min(-1).mmHg(-1); P < 0.05). In the HF group, LBNP elicited similar increases in MSNA (+11.5 + or - 2.0; P < 0.05) and PNE (+0.85 + or - 0.12; P < 0.05), without affecting FVC significantly (-4.1 + or - 2.4; P = 0.01 vs. N, interaction P = 0.03). However, within the HF group, responses were bimodal: LBNP -40 mmHg increased MSNA in all subjects (P < 0.001), yet the six patients with nonischemic or dilated cardiomyopathy (DCM) exhibited significant vasoconstriction (decrease in FVC; P = 0.001), whereas the six patients with ischemic cardiomyopathy (ICM) exhibited significant vasodilation (increase in FVC; P < 0.02 vs. DCM and N; interaction P = 0.02). Cold pressor testing increased MSNA and decreased FVC in ICM (n = 4). Thus paradoxical forearm vasodilator responses to LBNP in HF are not mediated by reflex sympathetic withdrawal. ICM and DCM patients differ qualitatively in their vascular responses to hypotensive LBNP.
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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) | 0.001 | 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".