Hemodilution Improves Shear‐Mediated Transduction of Vasodilatory Signals in Human Cerebral and Systemic Circulations
Bibliographic record
Abstract
Shear stress (SS) regulates blood flow within the systemic and cerebral circulation. For example, in clinical populations (e.g. hemochromatosis), endothelium‐dependent flow‐mediated dilation (FMD) is improved and impaired by increases and decreases in whole blood viscosity (WBV), respectively. We tested the hypothesis that reductions in WBV would attenuate both cerebrovascular CO 2 reactivity and brachial FMD in healthy males (n=9). Internal carotid (ICA) and brachial artery (BA) blood flow, as well as cerebrovascular CO 2 reactivity and FMD, were measured prior to and following isovolumic hemodilution with 5% human serum albumin (20% removal/replacement of blood volume). Hemodilution reduced hematocrit (42.7±2.5 vs. 34.7±2.0 %; P<0.01) and WBV (3.6±0.2 vs. 2.7±0.2 cP; P<0.01). Resting ICA blood flow increased by 19% (328.7±66.3 vs. 389.9±91.0 mL · dL − 1 ; P<0.01) while SS was unaltered (13.4±3.2 vs. 12.5±2.6 dyn · cm − 2 ; P=0.17). BA blood flow (41.0±18.9 vs. 54.6±34.1 mL · min − 1 ; P=0.31) and SS (2.54±1.15 vs. 3.00±2.83 dyn · cm − 2 ; P=0.66) were unaltered following hemodilution. Despite a similarly unaltered SS area under the curve stimulus (733.4±296.6 vs. 996.1±571.1 au 3 ; P=0.20), BA FMD increased by 130% (3.9±2.3 vs. 9.0±4.3%; P=0.02). In contrast, however, neither absolute [24.3±7.4 vs. 30.1±13.5 ΔCBF (mL/dL) · ΔmmHg PaCO 2 ; P=0.10] or relative [7.6±3.1 vs. 8.5±4.1 %ΔCBF · mmHg PaCO 2 ; P=0.28) CO 2 reactivity were altered following hemodilution despite a reduced SS stimulus throughout the reactivity test (main effect, P<0.01). Therefore, despite the differing influence of hemodilution on cerebral and systemic circulations, both were more responsive for a given SS stimulus following hemodilution. Support or Funding Information Ryan L. Hoiland was supported by a Natural Sciences and Engineering Research Council of Canada Post Graduate Scholarship. Dr. David MacLeod is supported through the Duke University Human Physiology & Pharmacology Laboratory. Prof. Philip Ainslie is supported by the Natural Sciences and Engineering Research Council of Canada and Canada Research Chairs. 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) | 0.001 | 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".