Sex Differences in Sympathetic Vasoconstrictor Responsiveness and Sympatholysis
Bibliographic record
Abstract
Sympathetic nervous system control of blood pressure and skeletal muscle vascular resistance appears to differ between males and females. The mechanism(s) responsible for sex differences in neurovascular control have not been fully elucidated. Nitric Oxide (NO) has been shown to inhibit sympathetic vasoconstriction in resting and contracting skeletal muscle and estrogen appears to modulate NO synthase (NOS) expression and NO bioavailability. The relative abundance of estrogen in females compared to males suggests that NO‐mediated inhibition of sympathetic vasoconstriction may be augmented in females relative to males. Therefore, the purpose of the present study was to investigate the hypothesis that compared to males, females would have blunted sympathetic vasoconstrictor responsiveness and augmented NO‐mediated inhibition of sympathetic vasoconstriction at rest and during exercise. Male (n=8) and Female (n=10) Sprague‐Dawley rats were anesthetized and surgically instrumented for measurement of arterial blood pressure and femoral artery vascular conductance (FVC) and stimulation of the lumbar sympathetic chain. The percentage change of FVC (%FVC) in response to sympathetic chain stimulation delivered at 2 and 5 Hz was determined at rest and during triceps surae muscle contraction before (control) and after NOS‐blockade (L‐NAME; 10 mg·kg −1 IV). At rest, vasoconstrictor responsiveness to sympathetic stimulation delivered at 2Hz was augmented (p<0.05) in females (−33 ± 8%) compared to males (−26 ± 6%), whereas vasoconstrictor responsiveness to sympathetic stimulation delivered at 5Hz was not different (p>0.05) between females (−55 ± 7%) and males (−47 ± 7%). Muscle contraction blunted (p<0.05) sympathetic vasoconstrictor responsiveness in both female and male rats; however the magnitude of sympatholysis was greater (p<0.05) in female (2Hz: 22 ± 8%; 5Hz: 30 ± 7%) compared to male (2Hz: 12 ± 6%; 5Hz: 13 ± 8%) rats. NOS blockade did not alter (p>0.05) sympatholysis of responses evoked at 2Hz in females or males; however L‐NAME reduced (p<0.05) sympatholysis of responses evoked at 5Hz in female rats. These data demonstrate that resting sympathetic vasoconstrictor responsiveness was augmented in female rats compared to male rats in a stimulation frequency‐dependent manner. Furthermore, sympatholysis was enhanced in female compared to male rats and this was partly attributable to augmented NO‐mediated inhibition of sympathetic vasoconstriction. Support or Funding Information Natural Sciences and Engineering Research Council of Canada (NSERC), Canadian Foundation for Innovation, and Alberta Advanced Education and Technology.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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) | 0.003 | 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".