On-line venous oxygen tensions in rainbow trout during graded exercise at two acclimation temperatures
Bibliographic record
Abstract
For most teleost fish, the majority of the myocardial oxygen supply is provided by the oxygen reserve remaining in venous blood after other tissues have extracted oxygen. We examined the effect of graded exercise and water temperature on this venous blood oxygen supply to the heart (termed the cardiac circulation) by performing novel on-line measurements of venous partial pressure of oxygen (Pv(O(2))) using a fibreoptic micro-optode implanted in the ductus Cuvier of rainbow trout (Oncorhynchus mykiss). As expected, Pv(O(2)) decreased progressively and significantly as swimming velocity approached the critical swimming speed (U(crit)). Unsteady swimming behaviours during the graded exercise, however, caused abrupt and generally short-lived decreases in Pv(O(2)). For the cold-acclimated (6-10 degrees C) fish, Pv(O(2)) reached a minimum plateau value of 15.3+/-3.7 torr (1 torr=133.3 Pa) before U(crit) was reached, and so increased swimming effort near to U(crit) did not reduce Pv(O(2)) further. Warm-acclimated fish had a significantly higher Pv(O(2)) (28.9+/-3.5 torr) at U(crit). Despite this difference in the Pv(O(2)) at U(crit), we estimated that there was little difference between warm- and cold-acclimated fish in terms of oxygen supply in the cardiac circulation because of a right-shift in the haemoglobin-oxygen dissociation curve at warm temperatures. Furthermore, although Pv(O(2)) decreased significantly at U(crit), our estimates suggest that the expected increase in cardiac output would easily maintain the oxygen supply in venous blood at a level similar to that found in resting fish. Although unsteady swimming behaviours decreased Pv(O(2)), unsteady swimming rarely decreased the minimum Pv(O(2)) value observed at U(crit) by more than 10%. The findings are discussed in terms of a threshold Pv(O(2)) required to maintain adequate rates of oxygen diffusion from the cardiac circulation to the myocardial tissues.
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 distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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 teacher head, 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".