Effects of neonatal hypoxia in the rat on inotropic stimulation of the adult heart
Bibliographic record
Abstract
OBJECTIVE: To determine whether transient hypoxia in neonatal rats has long-lasting effects on inotropic stimulation of the adult heart. METHODS: The hearts of adult male Sprague-Dawley rats (89+/-1 (S.E.M.) days, 432+/-5 g) were studied. Half the animals had been subjected to neonatal hypoxia (FiO(2)=0.12, days 1-10) while the others had not. The peak response of left ventricular pressure (LVP) and the maximum rate of pressure increase (+dP/dtmax) were measured in isolated and perfused hearts during application of dobutamine, isoproterenol, milrinone and betaxolol. Left ventricular myocyte membranes were analyzed for beta receptor density, adenylyl cyclase activity and content. RESULTS: LVP and +dP/dtmax responses to stimulation with dobutamine and isoproterenol were significantly impaired in adult hearts of neonatally hypoxic rats. The inotropic effect of dobutamine was abolished by blockade with the beta(1)-selective antagonist betaxolol. The inotropic effects of the phosphodiesterase inhibitor milrinone were also significantly decreased in neonatally hypoxic adult hearts. There was no difference in left ventricular myocyte membrane beta receptor density of adult hearts whether they were hypoxic neonatally or not. However, left ventricular adenylyl cyclase activity on isoproterenol or forskolin stimulation and adenylyl cyclase levels (type V/VI) were significantly reduced in neonatally hypoxic adult hearts. CONCLUSIONS: Neonatal hypoxia in the rat has long-lasting effects on the left ventricular response to inotropic stimulation at maturity likely at least in part due to diminished left ventricular adenylyl cyclase levels.
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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) | 0.002 | 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".