Effect of Hindlimb Unloading on Salt and Water Intake and Output in Male and Female Rats
Bibliographic record
Abstract
INTRODUCTION/PURPOSE: Although fluid intake decreases during spaceflight, there is no increase in urine output, despite the microgravity-induced cephalic fluid shifts. We proposed that fluid and electrolyte balance is controlled not only by cardiac receptors but also by splanchnic baroreceptors. METHODS: Male and female rats bearing indwelling intravenous cannulae, were subjected to hindlimb unloading (HU) for 24 h at 30 degrees . Water and salt (3% saline) intake, urine output, and plasma osmolality were measured. Right atrial pressure (RAP) and splenic blood pressure/flow were measured during tilt. RESULTS: Whereas HU reduced water intake in both males (100.9 +/- 9.0 to 71.8 +/- 6.1 mL.kg) and females (118.9 +/- 8.9 to 83.1 +/- 6.5 mL x kg), there was a sustained increase in urine volume only in females (males: 30.9 +/- 3.8 to 34.0 +/- 2.8 mL.kg; females: 26.3 +/- 3.8 to 41.1 +/- 5.8 mL.kg). HU did not change sodium intake/output in either males or females. Plasma osmolality (321.8 +/- 24.1 to 347.5 +/- 22.7 mOsm x L) increased in females but not in males (349.2 +/- 3.3 to 354.4 +/- 7.7 mOsm x L). HU was associated not only with increased RAP but also with reduced splenic perfusion: splenic venous pressure/flow decreased by 0.90 +/- 0.16 mm Hg and 0.19 +/- 0.01 mL.min, respectively; splenic arterial pressure/flow decreased by 3.97 +/- 1.68 mm Hg and 0.17 +/- 0.06 mL x min, respectively. CONCLUSION: We propose that it is the balance between discordant signals from cardiac and splenic baroreceptors that controls ingestion and excretion. The ultimate reflex response thus depends on the differential effects of changes in gravity on systemic hemodynamics.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.004 | 0.001 |
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".