Short‐term exercise training augments α<sub>2</sub>‐adrenoreceptor‐mediated sympathetic vasoconstriction in resting and contracting skeletal muscle
Bibliographic record
Abstract
Key points Postsynaptic α1‐ and α2‐adrenoreceptors produce tonic vasoconstriction in resting and contracting skeletal muscle. Muscular contraction attenuates sympathetic vasoconstriction (functional sympatholysis). The blunting of sympathetic vasoconstriction during contraction has been mechanistically linked to a reduction in postsynaptic α1‐ and α2‐adrenoreceptor responsiveness and nitric oxide. We recently demonstrated that exercise training augmented sympathetic vasoconstrictor responsiveness and functional sympatholysis. Whether these vascular adaptations were mediated by changes to postsynaptic adrenoreceptors was not investigated. The present findings demonstrate that exercise training augmented α2‐adrenoreceptor‐ mediated vasoconstriction in resting and contracting skeletal muscle. These data indicate that exercise training alters the relative contributions of α‐adrenoreceptors to sympathetic vasoconstriction in resting and contracting skeletal muscle and that the regulation of sympathetic vasoconstriction becomes more complex following exercise training. Abstract We hypothesized that exercise training (ET) would alter α2‐adrenoreceptor‐mediated sympathetic vasoconstriction. Sprague‐Dawley rats (n= 30) were randomized to sedentary (S), mild‐ (M) or heavy‐intensity (H) treadmill ET groups (5 days per week for 4 weeks). Following the ET component of the study, rats were anaesthetized, and instrumented for lumbar sympathetic chain stimulation, triceps surae muscle contraction and measurement of femoral vascular conductance (FVC). The percentage change of FVC in response to sympathetic stimulation was determined at rest and during contraction in control, α2blockade (yohimbine) and combined α2+ nitric oxide (NO) synthase (NOS) blockade (Nω‐nitro‐l‐arginine methyl ester hydrochloride,l‐NAME) conditions. ET augmented (P< 0.05) sympathetic vasoconstrictor responses at rest and during contraction. Yohimbine reduced (P< 0.05) the vasoconstrictor response in ET rats at rest (M: 2 Hz: 8 ± 2%, 5 Hz: 9 ± 4%; H: 2 Hz: 14 ± 5%, 5 Hz: 11 ± 6%) and during contraction (M: 2 Hz: 9 ± 2%, 5 Hz: 9 ± 5%; H: 2 Hz: 8 ± 3%, 5 Hz: 6 ± 6%) but did not change the response in S rats. The addition ofl‐NAME caused a larger increase (P< 0.05) in the vasoconstrictor response in ET than in S rats at rest (2 Hz: S: 8 ± 2%, M: 15 ± 3%, H: 23 ± 7%; 5 Hz: S: 8 ± 5%, M: 15 ± 3%, H: 17 ± 5%) and during contraction (2 Hz: S: 9 ± 3%, M: 18 ± 3%, H: 22 ± 6%; 5 Hz: S: 9 ± 5%, M: 22 ± 4%, H:26 ± 9%). Sympatholysis was greater (P< 0.05) in ET than in S rats. Blockade of α2‐adrenoreceptors and NOS reduced (P< 0.05) sympatholysis in ET rats, but had no effect on sympatholysis in S rats. In conclusion, ET increased α2‐mediated vasoconstriction at rest and during contraction.
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 | 0.001 |
| 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".