Intensity-dependent Effects Of Exercise Training On α1-adrenergic Receptor-responsiveness In The Skeletal Muscle Vasculature
Bibliographic record
Abstract
Arterial blood pressure and tissue perfusion are maintained by a dynamic balance between sympathetic vasoconstriction and locally mediated vasodilation. Exercise training is known to augment the vascular response to vasodilatory stimuli. The effects of exercise training on sympathetic vasoconstriction are less clear, as the available evidence is limited and contradictory. PURPOSE: To investigate the effect of 4 weeks of mild- and heavy-intensity exercise training on α1-adrenergic receptor-responsiveness in the skeletal muscle vasculature. HYPOTHESIS: It was hypothesized that exercise training would up-regulate α1-adrenergic receptor-responsiveness in an exercise- intensity dependent manner. METHODS: Sprague-dawley rats were randomly assigned to sedentary (S; n=8), mild- (M: 20m·min-1 5% grade; n=11) or heavy-intensity (H: 40m·min-1 5% grade; n=8) exercise groups. Rats were trained 5d·week-1 for 4 weeks with total training volume matched between exercise groups. Following training, rats were anesthetised and instrumented for study. Arterial blood pressure (brachial artery) and femoral artery blood flow were measured continuously. Femoral vascular conductance (FVC mL·min-1·mmHg-1) and resistance (FVR mmHg·mL·min-1) were calculated. The selective α1-adrenergic agonist phenylephrine (PE, 0.1 μg·mL·-1min-1) was infused intra-arterially. Comparisons between groups were assessed with one-way ANOVA and Student-Newman-Keuls post-hoc test. A p-value <0.05 was considered significant. RESULTS: Exercise training did not alter basal limb blood flow (S: 4±2 mL·min-1; M: 4±1 mL·min-1; H: 4±1 mL·min-1, p>0.05), or MAP (S: 95±11 mmHg; M: 94±15 mmHg; H: 94±14 mmHg, p>0.05). PE infusion elicited a training-intensity dependent decrease (% change from baseline) in FVC (S: -39±13%, M: -56±13%, H: -73±12%, p<0.05) and increase (% change from baseline) in FVR (S: 69±30%, M: 137±62%, H: 267±83% p<0.05). CONCLUSION: These data indicate that α1-adrenergic receptor-responsiveness is increased following 4 weeks of exercise training in a manner dependent upon the intensity of the training stimulus. Supported by NSERC, Canada.
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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) | 0.002 | 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".