β-Adrenergic receptor blockade impairs NO-dependent dilation of large coronary arteries during exercise
Bibliographic record
Abstract
Shear stress-dependent nitric oxide (NO) formation prevents immoderate vascular constriction. We examined whether shear stress-dependent NO formation limits exercise-induced coronary artery constriction after beta-adrenergic receptor blockade in dogs. Control exercise led to increases (P < 0.01) in coronary blood flow (CBF) by 38 +/- 5 ml/min from 41 +/- 5 ml/min and in the external diameter of epicardial coronary arteries (CD) by 0.24 +/- 0.03 mm from 3.33 +/- 0.20 mm. CD and shear stress were linearly related. After propranolol, CD fell (P < 0.01) during exercise (0.08 +/- 0.03 from 3.23 +/- 0.19 mm), and the slope of the relationship between CD and shear stress was reduced (P < 0.01). This slope was not further altered by the additional blockade of NO formation. In propranolol-treated resting dogs, flow-dependent effects of intracoronary adenosine to mimic exercise-induced increases in shear stress (after propranolol) led to increases (P < 0.01) in CD (0.09 +/- 0.02 from 3.68 +/- 0.27 mm). Thus both shear stress-dependent NO formation and beta-adrenergic receptor activation are required to cause CD dilation during exercise. Suppression of beta-adrenergic receptor activation leads to impaired shear stress-dependent NO formation and allows alpha-adrenergic constriction to become dominant.
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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 | 0.001 |
| 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".