Nitric oxide and sodium nitroprusside‐induced relaxation of the human umbilical artery
Bibliographic record
Abstract
In the human umbilical artery (HUA) pre-contracted with the thromboxane mimetic U46619 or with 5-hydroxytryptamine (5-HT), (and pretreated with indomethacin (3 microM) to suppress the synthesis of prostanoids), authentic nitric oxide (NO) evoked concentration-dependent relaxation (pEC(50) 7.05 and 5.99, respectively). In contrast, sodium nitroprusside (SNP) induced relaxation only in U46619 pre-contracted HUA (pEC(50) 6.52). At high (>300 mmHg) vs low (<55 mmHg) oxygen tension the dose-response curves to NO- and SNP-induced relaxations were biphasic and shifted leftward. Preincubation of the arterial rings with the soluble guanylyl cyclase (sGC) inhibitor 1H[1,2,4]oxadiazolo[4, 3-a]quinoxalin-1-one (ODQ; 10 microM) shifted the concentration-response curve to NO, reduced the maximal relaxation response to NO (E(max) 71%) and to SNP (E(max) 10%). Pre-exposure of HUA rings to high extracellular K(+) (50 mM) reduced E(max) relaxation responses to NO (36%) and SNP (1%). Pretreatment of the HUA with the K(+) channel inhibitors, tetraethylammonium (TEA, 1 mM), 4-aminopyridine (4-AP, 0.5 mM), charybdotoxin (0.1 microM) or iberiotoxin (0.1 microM) increased the pEC(30) for NO and SNP and changed the shape of the dose-response curves from biphasic to monophasic. Pre-incubation of HUA rings with TEA (1 mM), 4-AP (0.5 mM) and ODQ (10 microM) significantly reduced the NO-induced maximal relaxation (E(max) 26%) but not the pEC(50) (5.60). These data indicate that SNP-induced relaxation in the HUA is primarily mediated via sGC-cyclic GMP whereas NO-induced relaxation also involves the activation of K(V) and K(Ca) channels and a cyclic GMP/K(+) channel-independent mechanism(s).
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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 | 0.001 |
| 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".