Age‐related changes in vasoconstrictor response to heat in skeletal muscle arteries
Bibliographic record
Abstract
Aging reduces skeletal muscle blood flow, but the mechanism remains unclear. The hypothesis was that aging results in less heat‐induced attenuation of vasoconstriction and this is attributable to decreased sensitivity of P2X receptors to heat. Femoral arteries from 28 young (2–3 months old) and 23 old (24 months old) rats were prepared for wire myography. Dose response curves for the P2X agonist, αβ‐methylene ATP (mATP: 10 −7 to 10 −3 M), the α 1 ‐agonist, phenylephrine (PE: 10 −7 to 10 −4 M), the smooth muscle constrictor, potassium chloride (KCl: 20 to 80mM), and field stimulation (2–60Hz for 144 impulses) were performed at bath temperatures of 37°C and 41°C. The response to mATP was attenuated with heat in young (37°C: 0.95±0.14; 41°C: 1.48±0.12 g/log M mATP; p<0.05) and old (37°C: 1.05±0.16; 41°C: 1.67±0.20 g/log M mATP; p<0.05) femoral arteries. Phenylephrine dose response curves were not heat sensitive in young arteries, but were potentiated with 41°C in old arteries (p<0.05). KCl dose response curves were potentiated by 41°C in the young (37°C: 2.10±0.25; 41°C: 2.67±0.19g peak tension; p<0.05) and old arteries (37°C: 1.95±0.22; 41°C: 2.53±0.10g peak tension; p<0.05). The tension produced by field stimulation was attenuated by a greater amount in old (−78±10%) than in young (−43±12%). Heat‐induced attenuation of vasoconstriction via P2X receptors is preserved in old femoral arteries. Unexpectedly, old femoral arteries exhibit heat potentiation of α 1 ‐receptor mediated vasoconstriction.
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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 | 0.000 |
| 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) | 0.001 | 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".