Inhibition of NOS Does Not Affect Oxygen Dependent Capillary Blood Flow Response In Vivo
Notice bibliographique
Résumé
Objective To determine if nitric oxide (NO) plays a significant role in regulating blood flow, in response to changing oxygen (O 2 ) conditions within skeletal muscle capillaries. Methods Five male Sprague‐Dawley rats, 140 – 190g rats were anaesthetized with pentobarbital, tracheotomized, ventilated, and maintained in a normotensive state. A laparotomy was performed and the left common iliac was catheterized with a cannula advanced retrograde to the distal abdominal aorta. The extensor digitorum longus muscle was blunt dissected and reflected onto a glass cover slip (dose response), or permeable membrane above a gas exchange chamber (O 2 response) set within a microscope stage. The muscle was bathed in warm saline and isolated from the air via polyvinylidene chloride film and a glass coverslip. Dose response was determined in 3 animals by injecting a nitric oxide synthase inhibitor, L‐NMMA, in logarithmic increasing concentrations ranging from 10 −5 to 1 mg/kg into the iliac artery. O 2 dependent blood flow responses were determined in 2 animals. Gas concentrations (N 2 , CO 2 , and O 2 ) within the exchange chamber were dynamically controlled using mass flow valves connected to a computer. The muscle was allowed to equilibrate for 30 minutes at 5% CO 2 , 5% O 2 and 90% N 2 . O 2 concentrations at the surface of the muscle were oscillated from 7%–12%‐2%–7% in a square‐wave with each level maintained for 60s. CO 2 was held at a constant 5% with N 2 composing the balance of gas within the exchange chamber. Video sequences of capillary blood flow at 10× magnification were recorded in multiple fields in each animal. Videos were analyzed offline using custom software written in MATLAB yielding frame‐by‐frame measurements of capillary velocity, hematocrit and red blood cell supply rate (SR). Results Capillary blood flow dose response for L‐NMMA was measured in 178 capillaries under baseline, and increasing concentrations of L‐NMMA. All L‐NMMA concentrations caused a significant decrease in SR compared to vehicle () with a 42% reduction at 10 −2 mg/kg; higher doses did not result in a further decrease of SR. The time dependent O 2 blood flow response was measured in 58 capillaries under baseline conditions and after infusion of 10 −2 mg/kg L‐NMMA (). An average phase lag of 20 s was observed in the SR response to O 2 concentration changes in the chamber under both conditions. Phase lag was partially due to the intrinsic time delay of the gas delivery system. Average SR under 7% O 2 concentration was 45% lower with L‐NMMA compared to control. High O 2 caused a decrease in SR of 53% for control vs. 60% under L‐NMMA, normalized to the baseline mean SR at 7% O 2 . Low O 2 caused an increase in SR of 14% and 47% with control and L‐NMMA respectively. Post oscillation, 7% O 2 restored average SR to 93% and 100% of baseline in control and L‐NMMA respectively. Conclusion Alteration of tissue surface O 2 causes an O 2 dependent capillary blood flow response to both low and high O 2 challenges that is preserved following the introduction of a nitric oxide synthase inhibitor. This suggests that NO does not play a significant role in regulating blood flow, in response to changing O 2 conditions within skeletal muscle capillaries.
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,001 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,001 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».