Microvascular oxygen transport in rat skeletal muscle: temporal variability
Bibliographic record
Abstract
Oxygen delivery to a whole organ is closely regulated to match the metabolic needs of the tissue. But capillary blood flow at rest is characterized by considerable spatial and temporal heterogeneity suggesting that local regulation of O 2 delivery does not precisely maintain O 2 transport in individual capillaries. How precise is capillary O 2 transport regulated? To investigate this question, we used a dual wavelength optical imaging system to measure capillary O 2 transport in capillaries in extensor digitorum longus muscle of anesthetized rats for one minute periods every hour for three hours. From 5 to 15 capillaries were studied in six male Sprague‐Dawley rats with normal systemic parameters (arterial blood pressure, blood gases, hemoglobin O 2 saturations and hematocrit). There were no significant differences in mean capillary O 2 transport parameters for each animal over the three hour period (mean ± SD; velocity μm/s: 123 ± 49, 124 ± 49, 133 ± 57; hematocrit %: 17 ± 3.5, 17 ± 5.7, 16 ± 5.2; supply rate RBC/s: 9 ± 5.2, 9 ±3.5, 10 ± 5.9; oxygen saturation %: 60 ± 9.1, 63 ± 7.3, 62 ± 14.3). However, within each animal, O 2 transport parameters in individual capillaries increased or decreased from one hour to the next such that there was no significant correlation in any of these parameters over time. Although mean O 2 transport for a group of capillaries was maintained over time, O 2 transport was not regulated at the level of individual capillaries. Diffusional exchange among capillaries likely compensates for the heterogeneity in O 2 transport in capillaries. Research supported by an operating grant from Heart and Stroke Foundation of Ontario to CGE.
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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) | 0.000 | 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".