Muscarinic Receptor‐Mediated Regulation of Epineurial Blood Vessels of the Sciatic Nerve
Bibliographic record
Abstract
Objective The objective of this study was to determine the role of muscarinic receptors on the diameter of the epineurial vessels of the sciatic nerve in situ. Methods An anesthetized rat model (318.4±7.1 g) was used to expose the sciatic nerve and directly visualize its microvasculature using intravital video microscopy. Rats were tracheotomized and catheters were inserted into the jugular vein for supplemental anesthesia, and the carotid artery for measures of mean arteriolar pressure. Alexa Fluor 488 Isolectin GS‐IB4 conjugate (178.6 μm/ml) was topically applied for 10 minutes to the exposed sciatic nerve to stain the endothelial cells of the epineurial vessels of the nerve. Following a 30‐min equilibration period, acetylcholine (10 −4 M, n=8) or atropine (10 −5 M, n=6) was topically applied for 4 and 5 minutes, respectively. Images were captured at baseline (immediately prior to drug application) and every minute during the application period. The images were analyzed offline using ImageJ to measure the diameter of the vessels at each time point. All data are expressed as mean ± standard error. Results Acetylcholine caused a vasodilation of the epineurial vessels (baseline: 22.9±2.4 μm, acetylcholine: 29.2±2.9 μm, p<0.01). There was no difference in mean arteriolar pressure from baseline (103.8±1.5 mmHg) to maximum vasodilation (102.3±2.7 mmHg). Atropine caused a vasoconstriction of the epineurial vessels (baseline: 26.7±3.2 μm, atropine: 15.5±3.6 μm, p<0.05). There was no difference in mean arteriolar pressure from baseline (104.0±1.9 mmHg) to maximum vasoconstriction (105.2±2.2 mmHg). Conclusion Application of acetylcholine, a muscarinic receptor agonist, resulted in a vasodilation while application of atropine, a muscarinic receptor antagonist, caused vasoconstriction. This finding suggests that muscarinic receptors are involved in blood flow regulation of peripheral nerves. Further, since atropine constricted the vessels at baseline conditions, muscarinic receptors may be involved in maintaining baseline diameter. Support or Funding Information This study was supported by the SEED Research Grant from The University of Western Ontario. This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .
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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".